Nasal infix

The nasal infix is a reconstructed nasal consonant or syllable *⟨n⟩ that was inserted into the stem or root of a word in the Proto-Indo-European language. It has reflexes in several ancient and modern Indo-European languages. It is one of the affixes that mark the present tense.

Proto-Indo-European

In the Proto-Indo-European language, the nasal infix *⟨n⟩ is one of several means to form the athematic present tense. It is inserted immediately before the last consonant of the zero-grade root. The infix appeared as *⟨né⟩ in the forms where a full-grade stem would be expected, and as *⟨n⟩ in forms where zero-grade would be expected. For example, the PIE root *weik- "to win" would yield a nasal-infixed present stem *wi⟨né⟩k- ~ *wi⟨n⟩k-. These presents are called nasal infix presents or simply nasal presents and are typically active transitive verbs, often with durative aspect. Throughout the non-Anatolian branches of the Indo-European family, nasal-infix presents are often associated with root aorists.

Origins

Since the linguistic ancestor of PIE is not known, there can only be speculations about the origins of the nasal infix. It has been suggested that it arose from a suffix which underwent metathesis.

Other present tense markers

Besides the nasal infix, PIE employs a number of affixes to mark the present: *-u-, *-neu-, *-neH-, *-sḱe-, *-de-, and others. All in all, PIE has at least 18 ways to form the present tense. For many verbs, several of these presents can be reconstructed simultaneously. For example, Scottish Gaelic loisg "to burn" goes back to *l̥h₂p-sḱé-, a *sḱe-present of the root *leh₂p- which is also the source of Ancient Greek λάμπειν "to shine" via its nasal present *l̥h₂⟨n⟩p-.
It is not clear why there were so many different types of present forms with no or little discernible differences in meaning. The authors of the Lexikon der indogermanischen Verben proposed that they were derived from a number of prior grammatical aspects with distinct meanings.

Indo-European languages

The effects of the nasal infix can be seen in Indo-European languages like Sanskrit, Latin, Lithuanian, Armenian, Ancient Greek, the Goidelic languages, and the Slavic languages.
In Latin, Ancient Greek and other daughter languages, the *n was assimilated to m before labial consonants, and to ŋ, spelled n in Latin and γ in Ancient Greek, before velar consonants. Latin rūpit "has broken" / rumpit "breaks", from *rup- / *ru⟨n⟩p-, is an example of the first case.

Indo-Aryan

The phenomenon of nasal-infixing as inherited from Proto-Indo-European is found in Sanskrit with the greatest morphological transparency, and is taken as a guide to examining the feature in kindred languages.
Three of the ten classes identified by [Sanskrit grammar#Grammatical tradition|traditional Sanskrit grammarians] have nasal infix of some kind, which are higher-grade and accent-bearing in the strong forms, and reduced-grade in the weak forms. The behaviour of the class-7 root √yuj- class-5 √śru- and class-9 krī- can be seen thus:

yu·ná·k·ti ↔ yu·ñj·ánti
śṛ·ṇó·ti ↔ śṛ·ṇv·ánti
krī·ṇā́·ti ↔ krī·ṇ·ánti

While these were seen as 3 separate classes by the ancient Sanskrit grammarians, Ferdinand Saussure demonstrated, as part of his landmark work in postulating the Laryngeal theory, that these were slightly different manifestations of the same nasal infix.

Greek

Greek has some verbs that show a nasal infix in the present as opposed to other forms of the verb:

λαμβάνω against aorist ἔλᾰβον
λανθάνω against alternative λήθω
τυγχάνω against aorist ἔτυχον
Latin

Latin has a number of verbs with an n in the present stem which is missing in the perfect stem:

vīcit "has won" / vincit "wins"
contudit "has crushed" / contundit "crushes"
scidit "has cut" / scindit "cuts"
Latin loanwords

English and the other Germanic languages show only vestiges of the nasal infix. The only certain remaining example is English stand, with the past tense stood lacking the n. However, it can still be seen in some pairs of Latin loanwords:

In Celtic, the Indo-European nasal infix presents split into two categories: ones originally derived from laryngeal-final roots, and ones that were not. In seṭ verbs, the nasal appears at the end of the present stem, while in aniṭ-derived verbs the nasal was followed by a root-final stop. The nasal presents are readily apparent in Old Irish, where the nasal infix is not present outside of the present stem, like in other old Indo-European languages.

Meaning	Root type	Present	Preterite	Future	Subjunctive
"to support"	aniṭ	fo·loing ·fulaing	fo·lolaig	fo·lil	fo·ló
"to buy"	seṭ	crenaid ·cren	cíuir	*-cíuri	-cria

The seṭ nasal presents' final nasal, ultimately from the nasal infix, was generalized to become suffixed onto all verbs in modern Irish as the present analytic suffix -ann, remaining productive into modern times.

Slavic languages

Only vestiges are left, like Russian лечь : лягу , сесть : сяду .

Examples

This table shows some examples of PIE root aorists, their infixed present forms and the reflexes in an attested daughter language.
^†The Latin reflexes of the PIE aorist came to be used as the perfect.
^‡It is uncertain whether *sleh₂gʷ- had a nasal infix already in PIE, since Greek λαμβάνω is only attested after Homer.

Tolkien

In J. R. R. Tolkien's constructed languages Quenya and Sindarin spoken by the Elves, the nasal infix forms the past tense of many verbs. These are most clear in Quenya which shows the nasal infix in the past-tense forms ending in any consonant besides -m, -n, or -r. Thus, cen- "to see" has the past tense cen-në, but mat- "to eat" has not *mat-në but the metathesised mat-ë. The infix is more obscured in related Sindarin due to further sound changes but can be observed in verbs such as pedi "to speak" has the form pennin "I spoke" which shows the nasal infix and the -d- of pedi and assimilated to -n- following the infix.