Indo-European copula

A feature common to all Indo-European languages is the presence of a verb corresponding to the English verb to be.

General features

This verb has two basic meanings:

In a less marked context it is a simple copula, a function which in non-Indo-European languages can be expressed quite differently.
In a more heavily marked context it expresses existence.

The dividing line between these is not always easy to draw.
Some languages have shared these functions between several verbs: Irish, Spanish and Persian all have multiple equivalents of to be, making a variety of distinctions.
Many Indo-European languages also use the verb "to be" as an auxiliary for the formation of compound tenses. Other functions vary from language to language. For example, although in its basic meanings, to be is a stative verb, English puts it to work as a dynamic verb in fixed collocations.
The copula is the most irregular verb in many Indo-European languages. This is partly because it is more frequently used than any other, and partly because Proto-Indo-European offered more than one verb suitable for use in these functions, with the result that the daughter languages, in different ways, have tended to form suppletive verb paradigms.
This article describes the way in which the irregular forms have developed from a series of roots.

The Proto-Indo-European PIE roots

''*h₁es-''

The root *h₁es- was certainly already a copula in Proto-Indo-European.
The e-grade *h₁es- is found in such forms as English is, Irish is, German ist, Latin est, Sanskrit asti, Persian ast, Old Church Slavonic jestĭ.
The zero grade *h₁s- produces forms beginning with /s/, like German sind, Latin sumus, Vedic Sanskrit smas, etc.
In PIE, *h₁es- was an athematic verb in -mi; that is, the first person singular was *h₁esmi; this inflection survives in English am, Pashto yem, Persian am, Sanskrit asmi, Bengali first-person verb ending -ām, Old Church Slavonic esmĭ, etc.
This verb is generally reconstructed for Proto-Indo-European thus:

Person	Present indicative	Imperfect indicative	Subjunctive	Optative	Imperative
1st singular	*h₁és-mi	*h₁és-m̥	*h₁és-oh₂	*h₁s-iéh₁-m	—
2nd singular	*h₁és-i	*h₁és	*h₁és-esi	*h₁s-iéh₁-s	h₁és, h₁s-dʰí
3rd singular	*h₁és-ti	*h₁és-t	*h₁és-eti	*h₁s-iéh₁-t	*h₁és-tu
1st dual	*h₁s-uós	*h₁s-ué	*h₁és-owos	*h₁s-ih₁-wé	—
2nd dual	*h₁s-tés	*h₁s-tóm	*h₁és-etes	*h₁s-ih₁-tóm	*h₁s-tóm
3rd dual	*h₁s-tés	*h₁s-tā́m	*h₁és-etes	*h₁s-ih₁-tā́m	*h₁s-tā́m
1st plural	*h₁s-m̥ós	*h₁s-m̥é	*h₁és-omos	*h₁s-ih₁-mé	—
2nd plural	*h₁s-té	*h₁s-té	*h₁és-ete	*h₁s-ih₁-té	*h₁s-té
3rd plural	*h₁s-énti	*h₁s-énd	*h₁és-onti	*h₁s-ih₁-énd	*h₁s-éntu

The root bʰuH- or bʰuh₂- probably meant 'to grow', but also 'to become'.
This is the source of the English infinitive be and participle been. Also, for example, the Scottish Gaelic "future" tense bithidh; the Irish imperative bí, past bhí and future beidh; the Welsh bod ; Persian imperative bov, past bud and future bâš; and the Slavic infinitive and past, etc. for example Russian быть, был.
PIE bʰ became Latin /f/, hence the Latin future participle futūrus and perfect fuī; Latin fīō 'I become' is also from this root, as is the Greek verb φύω, from which physics and physical are derived.
bʰuH- was a preterite-present verb, i.e. imperfect endings for the present, and can be reconstructed as follows:

Person	Indicative	Subjunctive	Optative	Imperative
1st singular	*bʰúH-m	*bʰúH-oh₂	*bʰuH-yéh₁-m	—
2nd singular	*bʰúH-s	*bʰúH-esi	*bʰuH-yéh₁-s	bʰúH, bʰuH-dʰí
3rd singular	*bʰúH-t	*bʰúH-eti	*bʰuH-yéh₁-t	*bʰúH-tu
1st dual	*bʰuH-wé	*bʰúH-owos	*bʰuH-ih₁-wé	—
2nd dual	*bʰuH-tóm	*bʰúH-etes	*bʰuH-ih₁-tóm	*bʰuH-tóm
3rd dual	*bʰuH-tā́m	*bʰúH-etes	*bʰuH-ih₁-tā́m	*bʰuH-tā́m
1st plural	*bʰuH-mé	*bʰúH-omos	*bʰuH-ih₁-mé	—
2nd plural	*bʰuH-té	*bʰúH-ete	*bʰuH-ih₁-té	*bʰuH-té
3rd plural	*bʰuH-énd	*bʰúH-onti	*bʰuH-ih₁-énd	*bʰuH-éntu

''*h₂wes-''

The root *h₂wes- may originally have meant "to live", and has been productive in all Germanic languages. The e-grade is present in the German participle gewesen, the o-grade survives in English and Old High German was, while the lengthened e-grade gives us English were. See Germanic strong verb: Class 5.

''*h₁er-''

This has been claimed as the origin of the Old Norse and later Scandinavian languages' present stem: Old Norse em, ert, er, erum, eruð, eru; the second person forms of which were borrowed into English as art and are. It has also been seen as the origin of the Latin imperfect and future tenses.
However, other authorities link these forms with *h₁es- and assume grammatischer Wechsel, although this is not normally found in the present stem. Donald Ringe argues that the copula was sometimes unaccented in Pre-Proto-Germanic, which would have then triggered the voicing under Verner's law. He explains the Germanic first person singular form immi as such, deriving it from earlier ezmi, since -zm-, but not -sm-, was assimilated to -mm- in Germanic. Furthermore, the third person plural form sindi shows that this word, too, was unaccented. If the accent had been preserved, it would have become sinþi, but that form is not found in any Germanic language. In this view, it is likely that stressed and unstressed varieties of the copula existed side by side in Germanic, and the involvement of a separate root h₁er- is unnecessary.
The Latin forms could be explained by rhotacism.

''*steh₂-''

The root *teh₂- meant "to stand". From this root comes the present stem of the so-called "substantive verb" in Irish and Scottish Gaelic, tá and tha respectively, as well as taw in Welsh. On the absence of the initial s- in Celtic, see Indo-European s-mobile.
In Latin, stō, stare retained the meaning "to stand", until local forms of Vulgar Latin began to use it as a copula in certain circumstances. Today, this survives in that several Romance languages use it as one of their two copulae, and there is also a Romance tendency for a past participle derived from *steh₂- to replace the original one of the copula. See also Romance copula.
Although in Dutch this verb retains its primary meaning of "stand", it is used in an auxiliary-like function that only has a secondary meaning of "standing", for example: ik sta te koken. While it is not a full copula, it does have shades of meaning that resemble that of the Italian sto cucinando. The intransitive verbs zitten, liggen and lopen are used in similar ways.
In Swedish, which usually lacks gerund forms, the corresponding stå is often used similarly, along with sitta, ligga and gå.
In Hindustani the past tense of the copula honā "to be" which are «tʰā», «tʰe», «tʰī» and «tʰī̃» are derived from Sanskrit «stʰā». Gujarati has a cognate verb «tʰavũ» "to happen"; cf. Bengali aorist «tʰā-» as well.

The resulting paradigms

Indo-Iranian languages

Indic languages

Sanskrit

The Vedic Sanskrit root as is derived from the Indo-European root *h₁es-.
bhū is derived from Indo-European *bʰuH-.

Hindi-Urdu

In modern Hindi-Urdu, the Sanskrit verb अस् ' which is derived from the Indo-European root *h₁es- has developed into the present indicative forms of the verb होना ہونا '. The infinitive होना ہونا ' itself is derived from the Sanskrit verb root भू ' which is derived from Indo-European root b^huH-. The indicative imperfect forms of होना ہونا ' comes from Sanskrit स्थित ' "standing, situated" which are derived from the PIE root *steh₂-. होना ہونا is the only verb in Hindi-Urdu to have the present indicative, imperfect indicative, presumptive mood and the present subjunctive conjugations, and all the other verbs in Hindi-Urdu lack them.
The verb होना / ہونا can be translated as "to be", "to exist", "to happen" or "to have" depending on the context, and when used in the third person it could also be translated as "there is/are". Many verbs conjugations in Hindi-Urdu are derived from participles and hence are gendered and numbered, and they agree with either the object or the subject of the sentence depending on the grammatical case of the subject of the sentence. When the subject is in the ergative or the dative case the verb agrees in gender and number with the object of the sentence and with the subject when the subject is in the nominative case.

Bengali

Bengali is considered a zero copula language, however there are notable exceptions. In the simple present tense there is no verb connecting the subject to the predicative but when the predicate expresses ideas of existence, location, or possession, for such cases the verb আছ- can be roughly translated as "to exist" or "to be present".

In the past tense, the incomplete verb আছ- ' is always used as the copula, regardless of the nature of the predicative.
For the future tense and non-finite structures, the copula is supplied by the verb হওয়া, with the exceptions being the possessive and locative predicatives for which the verb থাকা is utilized.
Bengali does not have a verb for possession. Instead, possession in Bengali is expressed by the verb আছ- ' and the verb থাকা inflected with the possessed object and a genitive case for the possessor.

Bengali verbs are highly inflected and are regular with only few exceptions. They consist of a stem and an ending; they are traditionally listed in Bengali dictionaries in their "verbal noun" form, which is usually formed by adding -a to the stem: for instance, করা is formed from the stem কর. The stem can end in either a vowel or a consonant.

Nepali

The copula verb of Nepali has two sets of conjugations. The हो set is used in sentences that equate two things, like त्यो किताब हो The छ set is used in sentences that describe something, or locate where something is, like त्यो ठूलो छ. Singular present tense forms of the copulas in Nepali are shown in the table below:

Iranic languages

Persian

With regard to the function of the verb ‘to be’ as a copula, the most conspicuous feature of Modern Persian language is the evolution of an existential be, hast, out of ast. In fact, when studying the forms and functions of ‘to be’, one might find certain characteristics specific to Persian that are worth pondering upon— i.e. even without considering the diachronic evolution of Modern Persian language and its relation to Ancient Iranian languages whose usage of the verb ‘to be’ seems more close to Sanskrit. Paradoxically, despite the fact that Persian is apparently the only Indo-European language that has created an existential be out of the copula, it has simultaneously made an extreme use of the latter to produce a general paradigm for conjugating all Persian verbs.
Historically speaking, like most of Indo-European languages that make use of suppletive roots to denote ‘to be’, Persian integrates Proto-Indo-European verbs *h₁es- and *b^huH . Hence, while Persian infinitive būdan < PIE *b^huH forms the past stem of the verb or acts as an auxiliary verb in formation of pluperfect of other verbs, its present tense is solely based on the derivatives of PIE *h₁es-. It is, in fact, from the declension of PIE *h₁es- that six present stems have been created and assigned to the 1st, 2nd, and 3rd person singular and plural to act as the present-tense conjugation of Persian būdan, as shown in the following table.

	Persian	English	Persian	English
1st Person	-am	am	-īm	are
2nd Person	-ī	art	-īd	are
3rd Person	ast	is	-and	are

As an example, in the following sentences, the present forms of the verb 'to be' are used as copulas or predicates:

Persian	English
man doxtar-e to am.	I am thy daughter.
īn barādar-e man ast.	This is my brother.
to pedar-e man ī.	Thou art my father.

Furthermore, as endings added to the stem of the verbs, these declensional forms have been grammaticalized to shape a general paradigm for the grammatical conjugation of all other verbs; these endings were once auxiliary verbs which evolved into an enclitic. This generalized conjugational paradigm is also applied to the past tense of the verb būdan. However, what is linguistically notable, is the emergence of an existential be out of the copula, viz hast out of ast. The evolution of this exceptional form, might go back to ancient Iranian languages, where ast could have two variants. In the next phase, what we may call a pseudo-verb appeared, vis. the verb hastan has been analogically evolved from hast and has been conjugated like any other Persian verb.
The simple past conjugation of the verb būdan is in fact formed by a double-copula, in the sense that both the stem and the ending are copulas: the past stem of the verb būd- is derived from PIE *b^huH-, while the endings are from the suppletive form of PIE *h₁es- with the exception of 3rd person singular which has zero ending for the all Persian verbs in the past tense.

Singular	English	Enclitic copula	Plural	English	Enclitic copula
būdam	I was	ام -am	būdīm	we were	ايم -īm
būdī	thou wast	اى -ī	būdīd	you were	اید -īd
būd	he/she/it was	Ø	būdand	they were	اند -and

The present perfect conjugation of the verb būdan is a double copula paradigm as it is produced by addition of all enclitic copulas to the past participle of the verb: būde.

Singular	English	Enclitic copula	Plural	English	Enclitic copula
būdeam	I have been	-am	būdeīm	we have been	-īm
būdeī	thou hast been	-ī	būdeīd	you have been	-īd
būde ast	he/she/it has been	ast	būdeand	they have been	-and

The pseudo-verb hastan has only simple present tense; in addition, it is truly and purely existencial only in the case of third person singular. The fact is that the verb has been the product of this very case, as an "existential is", hast. For other persons the conjugation has to use enclitic copulas. These copulas are, in turn, derived from the declension of PIE *h₁es- ; as if the predicative "to be" has been an auxiliary verb turned into enclitic, to provide six endings for 1st/2nd/3rd person. However, as it is said, the 3rd person singular has no ending in the case of hastan. That is to say that the existential hast, which is like the alter-ego of the copula ast, takes no ending, while the present stem of all other verbs take an archaic ending -ad in their 3rd person singular.

Singular	English	Enclitic copula	Plural	English	Enclitic copula
hastam	I exist	-am	hastīm	we exist	-īm
hastī	thou existest	-ī	hastīd	you exist	-īd
hast	he/she/it exists	> Ø	hastand	they exist	-and

Hellenic languages

Greek

The Ancient Greek verb eimi is derived from the Indo-European root h₁es-.
Dual is not shown in the table.
The participles are based on the full-grade stem ἐσ- in Homeric, according to Smyth.

Italic languages

Except for Latin, the older Italic languages are very scarcely attested, but we have in Oscan set, fiiet, fufans and fust, and in Umbrian sent. This section will explain Latin, and the Romance languages that have evolved from it.
Esse and the forms beginning with s- are from the root *h₁es-, while the forms beginning with f- are from the root bʰuH-. For the forms beginning with er-, see h₁er-. Stāre is derived from the root *steh₂-.
In Spanish, Catalan, Galician-Portuguese and to a lesser extent, Italian there are two parallel paradigms, ser/èsser/essere from Latin esse "to be" on the one hand, and estar/stare from Latin stare, "to stand" on the other.
In several modern Romance languages, the perfect is a compound tense formed with the past participle as in English, but the old Latin perfect survives as a commonly used preterite in Spanish and Portuguese, and as a literary "past historic" in French, Italian and Catalan.
There is a tendency for a past participle derived from stare to replace that of the main copula derived from esse. For example, the French participle été comes from statum.

Germanic languages

The proto-Germanic verb for 'to be', *wesaną, and its conjugations are mostly derived from the Proto-Indo-European verb *h₂wes. The present subjunctive stem is derived from the optative of *h₁es-. West Germanic languages also have an additional stem *bi-, which is thought to derive from the PIE stem *bʰuh₂-. Proto-Germanic retained the dual, but only in the first and second person.

Old English kept the verbs wesan and bēon separate throughout the present stem, though it is not clear that the kind of consistent distinction in usage was made that we find, for example in Spanish. In the preterite, however, the paradigms fell together. Old English has no participle for this verb.
The plural forms in Modern Swedish were in common use in formal written language until the mid-20th century, but are now no longer in use except in deliberately archaising texts. The preterite subjunctive is also increasingly being replaced by the indicative, or past participle.
Dutch, like English, has abandoned the original second-person singular forms, replacing them with the second-person plural forms. However, while in English the old forms are still in limited and deliberately archaic use, in Dutch they have disappeared entirely and are no longer known or used at all. The forms listed in the plural are the historical plural forms, the 'jij' and 'gij' forms. Dutch formed a new plural pronoun 'jullie' with inflection similar to the 1st and 3rd person plural, but it would be redundant to list them here.
Slavic languages

	Proto-Slavic	Old Church Slavonic	Ukrainian	Russian	Old Polish	Polish	Czech	Slovak	Slovenian	Serbo-Croatian	Bulgarian
Present	*esmĭ esi estĭ esvě esta este esmŭ este sǫtĭ	ѥсмь, jesmĭѥси, jesi ѥстъ, jestŭ ѥсвѣ, jesvě ѥста, jesta ѥсте, jeste ѥсмъ, jesmŭ ѥсте, jeste сѫтъ, sǫtŭ	є, je / – – – сьмо, сте,	есть, jest' – – –	jeśm jeś jest, jeść – – – jeśmy jeście są	jestem, -m jesteś, -ś jest – – – jesteśmy, -śmy jesteście, -ście są	jsem jsi je – – – jsme jste jsou	som si je – – – sme ste sú	sem si je sva sta sta smo ste so	jesam, sam/budem* jesi, si/budeš jest, je/bude – – – jesmo, smo/budemo jeste, ste/budete jesu, su/budu	съм, səm си, si е, e – – – сме, sme сте, ste са, sə
Imperative	– bǫdi bǫdi bǫděvě bǫděta – bǫděmŭ bǫděte bǫdǫ	–бѫди, bǫdi бѫди, bǫdi бѫдѣвѣ, bǫděvě бѫдѣта, bǫděta – бѫдѣмъ, bǫděmŭ бѫдѣте, bǫděte бѫдѫ, bǫdǫ	– будь, buď – – – – будьмо, buďmo будьте, buďte –	– будь, bud’ – – – – – будьте, bud’te –	– bądź – – – – bądźmy bądźcie –	– bywaj/bądź – – – – bywajmy/bądźmy bywajcie/bądźcie –	– buď – – – – buďme buďte –	– buď – – – – buďme buďte –	– bodi – bodiva bodita – bodimo bodite –	– budi – – – budimo budite	– бъди, bədi – – – – – бъдете, bədete –
Future	*bǫdǫ bǫdešĭ bǫdetĭ bǫdevě bǫdeta bǫdete bǫdemŭ bǫdete bǫdǫtĭ	бѫдѫ, bǫdǫбѫдеши, bǫdeši бѫдетъ, bǫdetŭ бѫдевѣ, bǫdevě бѫдета, bǫdeta бѫдете, bǫdete бѫдемъ, bǫdemŭ бѫдете, bǫdete бѫдѫтъ, bǫdǫtŭ	буду, budu будеш, budeš буде, bude – – – будемо, budemo будете, budete будуть, buduť	буду, budu будешь, budeš' будет, budet – – – будем, budem будете, budete будут, budut	będę będziesz będzie – – – będziemy będziecie będą	będę będziesz będzie – – – będziemy będziecie będą	budu budeš bude – – – budeme budete budou	budem budeš bude – – – budeme budete budú	bom, bodem boš, bodeš bo, bode bova, bodeva bosta, bodesta bosta, bodesta bomo, bodemo boste, bodeste bodo, bojo	budem budeš bude – – – budemo budete budu	ще бъда, šte bədə ще бъдеш, šte bədeš ще бъде, šte bəde – – – ще бъдем, šte bədem ще бъдете, šte bədete ще бъдат, šte bədət
Imperfect	*běaxŭ běaše běaše běaxově běašeta běašete běaxomŭ běašete běaxǫ	бѣахъ, běaxŭбѣаше, běaše бѣаше, běaše бѣаховѣ, běaxově бѣашета, běašeta бѣашете, běašete бѣахомъ, běaxomŭ бѣашете, běašeте бѣахѫ, běaxǫ			biech biesze biesze – – – biechom bieszecie biechą					bijah, beh bijaše, beše bijaše, beše – – – bijasmo, besmo bijaste, beste bijahu, behu	бях, bjah бе, be бе, be – – – бяхме, bjahme бяхте, bjahte бяха, bjahə
Aorist	*byxŭ by by byxově bysta byste byxomŭ byste byšę	бꙑхъ, byxŭбꙑ, by бꙑ by бꙑховѣ, byxově бꙑста, bysta бꙑсте, byste бꙑхомъ, byxomŭ бꙑсте, byste бꙑшѧ, byšę			bych by by – – – bychom byście bychą
Conditional copula						bym byś by – – – byśmy byście by	bych bys by – – – bychom byste by		bi bi	bih bi bi – – – bismo biste biše	бих, bih би, bi би, bi – – – бихме, bihme бихте, bihte биха, bihə
Present active participle	*sy m. sǫťi f. sy n.	сꙑ, sy m.сѫщи, sǫšti f. сꙑ, sy n.			sący m. sąca f. sące n.		jsoucí
Future active participle	*bǫdy m. bǫdǫťi f. bǫdy n.	бѫдꙑ, bǫdy m.бѫдѫщи, bǫdǫšti f. бѫдꙑ, bǫdy n.		будущий, buduščij m. будущая, buduščaja f. будущее, buduščeje n.	będący m. będąca f. będące n.	będący m. będąca f. będące n.	budoucí m. budoucí f. budoucí n.	budúci m. budúca f. budúce n.	bodoči m. bodoča f. bodoče n.	budući m. buduća f. buduće n.
Present gerund			будучи		sąc będąc	będąc	jsa jsouc jsouce				бъдейки
Past active participle	*byvŭ m. byvŭši f. byvŭ n.	бꙑвъ, byvŭ m.бꙑвъши, byvŭši f. бꙑвъ, byvŭ n.		бывший, byvšij m. бывшая, byvšaja f. бывшее, byvšeje n.	bywszy m. bywsza f. bywsze n.	bywszy m. bywsza f. bywsze n.		byvší m. byvšia f. byvšie n.	bivši m. bivša f. bivše n.	bivši m. bivša f. bivše n.
Past gerund			бувши		bywszy	bywszy	byv byvši byvše				-
Resultative participle	*bylŭ m. byla f. bylo n.	бꙑлъ, bylŭ m.бꙑла, byla f. бꙑло, bylo n.	був, buw m. була, bula f. було, bulo n.	был, byl m. была, byla f. было, bylo n.	był m. była f. było n.	był m. była f. było n.	byl m. byla f. bylo n.	bol m. bola f. bolo n.	bil m. bila f. bilo n.	bio m. bila f. bilo n.	бил, bil m. била, bila f. било, bilo n.
Verbal or deverbal noun	*bytĭje	бꙑтиѥ, bytije	буття́, buttja	бытьё, bytʹjó	bycie	bycie	bytí	bytie	bītje	biće	-
Infinitive	*byti	бꙑти, byti	бути, buty	быть, byt'	być	być	být	byť	biti	biti	-
Supine	-	-	-	-	-	-	-	-	bit	-	-

In Russian, the present forms are archaic and no longer in common use, except for the third person forms, which are used in "there is/are" type phrases.
In Ukrainian, the present tense forms of the verb "бути" have all but disappeared from contemporary language, except for the third person form which is used in existential phrases; єсть is archaic and encountered only in poetry. All participles have turned into other parts of speech, future and past active participles becoming present and past active adverbial participle respectively, and resultative pariciple becoming past tense of verbs.
In Serbo-Croatian the forms jesam, jesi, jeste and so on are used as the basic form of the Present Tense "to be", while the forms budem, budeš, bude etc. are used only for the formation of the Future Perfect.
In Bulgarian, forms бъда, бъдеш, etc. are not used by themselves but only in compound forms. In this respect they closely follow the usage of perfective verbs. As such it has its own forms for the aorist, the imperfect and the resultative participle. Another verb - бивам with fully regular conjugation type III paradigm - completes an aspect in Slavic languages|aspect] triple: imperfective съм, perfective бъда, secondary imperfective бивам. The perfective aorist has lost its original meaning and is now used only to form the compound conditional mood. All participles except the resultative participle have lost their function and are now used as regular adjectives with changed meanings.
In Polish, the present forms, except for jest and są, have turned into suffixes used primarily to construct the past tense and the conditional clitic. The modern conjugation comes from attaching these suffixes onto the third person singular form ''jest.''
Baltic languages

	Lithuanian	Latvian
Infinitive	būti	būt
Present	esu, esmi, esmì, būnu esì, būni yra, esti, estì, esa, būna esmè, esame, būname estè, esate, būnate yra, esti, esa, būna	esmu, esu esi ir esam esat ir
Past simple	buvau buvai buvo buvome buvote buvo	biju biji bija bijām bijāt bija
Past active participle	buvęs buvusi buvę buvusios	bijis bijusi bijuši bijušas
Future	būsiu būsi bus būsime būsite bus	būšu būsi būs būsim būsiet, būsit būs
Imperative	– būk – būkime būkite –	– esi – būsim esiet –
Quotative		esot, būšot
Conditional	būčiau būtum būtų būtumėme būtumėte būtų	būtu

In Lithuanian, the paradigm būnu, būni, būna, etc. is not considered archaic or dialectal but rather a special use of the verb būti, to be, mostly used to describe repeated actions or states, or habits.

Celtic languages

In the Celtic languages there is a distinction between the so-called substantive verb, used when the predicate is an adjective phrase or prepositional phrase, and the so-called copula, used when the predicate is a noun.
The conjugation of the Old Irish and Middle Welsh verbs is as follows:

	Old Irish substantive verb	Old Irish copula	Middle Welsh
Present	·tó ·taí ·tá ·taam ·taïd ·taat	am at is ammi adib it	wyf wyt yw, mae, taw, oes ym ych ynt, maen
Preterite	·bá ·bá ·boí ·bámmar ·baid ·bátar	basa basa ba bommar unattested batar	buum buost bu buam buawch buant
Future	bia bie bieid, ·bia beimmi, ·biam bethe, ·bieid bieit, ·biat	be be bid bimmi unattested bit	bydaf bydy byd bydwn bydwch bydant

The forms of the Old Irish present tense of the substantive verb, as well as Welsh taw, come from the PIE root *stā-. The other forms are from the roots *es- and *bhū-. Welsh mae originally meant "here is".

Irish and Scottish Gaelic

In modern Gaelic, person inflections have almost disappeared, but the negative and interrogative are marked by distinctive forms. In Irish, particularly in the south, person inflections are still very common for the tá/bhí series.

The verb bí

† archaic forms
Gaelic eil and Irish fuil are from Old Irish fuil, originally an imperative meaning "see!", then coming to mean "here is", later becoming a suppletive dependent form of at-tá. Gaelic robh and Modern Irish raibh are from the perfective particle ro plus ba.

The copula

Modern Welsh

The present tense in particular shows a split between the North and the South. Though the situation is undoubtedly more complicated, King notes the following variations in the present tense as spoken :
For example, the spoken first person singular dw i'n is a contraction of the formal written yr ydwyf fi yn . The Welsh F /v/ is the fricative analogue of the nasal /m/, the PIE suffix consonant for the first person singular.
Bod also has a conditional, for which there are two stems. The bas- stem is more common in the North, and the bydd- stem is more common in the South:

Hittite

The Hittite verb "to be" is derived from the Indo-European root h₁es-.

	Present indicative	Preterite indicative	Imperative
1st sg.	ēšmi	ešun	ēšlit ēšlut ašallu
2nd sg.	ēšši	ēšta	ēš
3rd sg.	ēšzi	ēšta	ēšdu
1st pl.		ēšwen	–
2nd pl.	ēšteni	ēšten	ēšten
3rd pl.	ašanzi	ešer	ašandu

Armenian

The Classical Armenian present tense derives from PIE h₁es-.

	present
1st sg.	em
2nd sg.	es
3rd sg.	ē
1st pl.	enkʿ
2nd pl.	ēkʿ
3rd pl.	en

Albanian

The Albanian copula shows two distinct roots. The present jam ‘I am’ is an athematic root stem built from PIE h₁es-. The imperfect continues the PIE imperfect of the same root but was rebuilt based on the 3rd person singular and plural. The preterite, on the other hand, comes from the thematic aorist of PIE kʷel- ‘turn’. Analogical or otherwise indirect reflexes are italicized below.

	PIE	present	PIE → PAlb	rebuilt	imperfect	imperfect	PIE → PAlb	preterite
1st sg.	*h₁ésmi	jam	h₁és-m̥ → eham	*eśen	jeshë	isha	kʷl-e-m̥ → klen^†	qeshë, OAlb qeva
2nd sg.	*h₁ési	je	h₁és → eh	*eśeh	jeshe	ishe	kʷl-e-s → kleh	qe
3rd sg.	*h₁ésti	ishtë ësht	h₁és-t → eśt	*eśt	je	ish → ishte	kʷl-e-to → kleta	kle → qe
1st pl.	*h₁s-méi	jemi	h₁s-m̥é → emma/e	*eśema/e	jeshëmë	ishim	kʷl-e-mé → klema/e	qemë
2nd pl.	*esi + -ni	jeni	h₁s-té → eśtā	*eśetā	jeshëtë	ishit	kʷl-e-té → kletā	qetë
3rd pl.	*h₁s-nti	janë	h₁s-énd → eśend	*eśend	ishinë	ishin	kʷl-e-nd → klend	qenë