Ancient Greek present progressive markers

Ancient Greek verbs often alter the stem in the present system with a variety of markers. These markers are best understood as markers of the continuous and progressive aspects, rather than of the present tense.
For verbs with progressive markers, the present progressive system is not the best guide to the true stem, which is often more clearly manifested in the aorist or future tense forms. Note that none of these markers was productive in the Classical period, although many verbs had alternate forms with and without the markers even into the Hellenistic period and later. Many of these markers date back to Proto-Indo-European and have clear parallels in other Indo-European languages. However, some Ancient Greek grammars and textbooks list and discuss these markers to help students grappling with the confusing morphology of Ancient Greek verbs.

*y yod marker

Ancient Greek has no consonant that makes the Y sound, similar to the Latin consonantal I in words like,, but it was part of Indo-European phonology, and it left detectable marks. The *y progressive marker has several manifestations, of which this chart is an incomplete overview:

Dentals	+ y =	ζ
Velar/Palatals	+ y =	ττ- /σσ-
Lambda (liquid)	+ y =	λλ-
Labials	+ y =	πτ-
ν	+ y =	ιν
ρ	+ y =	ιρ

stem	marker	progressive	aorist
θαυματ-	y		ἐθαύμασα
ἐλπίδ-	y		ἤλπισα
ἅλ-	y		ἡλόμην
πραγ-	y	/ πράττω	ἔπρᾱξα
ταραχ-	y	/ ταράττω	ἐτάραξα
ταγ-	y	/ τάττω	ἔταξα
τεν-	y		τενῶ
χαρ-	y		ἐχάρην
βλαβ-	y		ἔβλαβον
καλυβ-	y		ἐκάλυψα
κλεπ-	y		ἔκλεψα
σκεπ-	y		ἐσκεψάμην
ἅφ-	y		ἧψα
θαφ-	y		ἔθαψα

"The I Class", in Curtius, Georg. The Greek Verb: Its Structure and Development. Translated by Augustus S Wilkins and E. B England. London: J. Murray, 1880.

ΣΚ inchoative marker

This marker appears to be an Indo-European root for beginning an action, changing into a condition, an inchoative marker.

stem	marker	progressive	aorist
πάθ-	σκ		ἔπαθον
εὑρ-	σκ		ηὗρον
δά-	σκ		ἐδίδαξα
θαν-	σκ		ἔθανον
μνα-	σκ		ἔμνησα

Compare Latin verbs with similar inchoative SC markersnosco " get to know" from gno-sco cresco "grow" from cre – sco dormisco "fall asleep" obdormisco "go to sleep"duresco, "become hard"vesperasco "become evening"proficiscor, proficiscī, profectus sum "set out"rubescō, rubescere, rubuī "grow red, redden"

Ν nu marker

Ancient Greek often adds an N in the progressive forms of verbs. So often, in fact, that the most common verbs have N added twice into the stem.
Note that a N in Ancient Greek often expands to αν

stem/root	marker	progressive	aorist
ταμ-	ν		ἔταμον
αἰσθ-	ν		ᾐσθόμην
δακ-	ν		ἔδακον
ἱκ-	ν	,	ἱκόμην
κυ-	ν		ἔκυσα
αὐξ-	ν		ηὖξον

stem/root	marker	progressive	aorist
λαβ-	2ν		ἔλαβον
λαθ-	2ν		ἔλαθον
μαθ-	2ν		ἔμαθον
τυχ-	2ν		ἔτυχον
πυθ-	2ν		ἐπυθόμην
λαχ-	2ν		ἔλαχον

See in Curtius, Georg. The Greek Verb: Its Structure and Development. Translated by Augustus S Wilkins and E. B England. London: J. Murray, 1880.
in Kühner, Raphael. Ausführliche Grammatik Der Griechischen Sprache. Edited by Friedrich Blass and Bernhard Gerth. 3. Aufl. ed. Hannover: Hahnsche Buchhandlung, 1890, vol 1 part 2, p. 173

Ε epsilon progressive marker

Ancient Greek progressive forms will sometimes add an E into the vowel of the root. The first four verbs in the following list lengthen the vowel with an epsilon in progressive forms.
In an unrelated phenomenon, Ancient Greek will sometimes add an epsilon at the end of the root in the progressive forms. Many verbs have two progressive forms in Homer and other poets, one with and without the added epsilon, such as κυρέω and κύρω, ξύρω and ξυρέω, αἰδέομαι and αἴδομαι.

stem/root	marker	progressive	aorist
λιπ-	ε		ἔλιπον
φυγ-	ε		ἔφυγον
πιθ-	ε		ἔπιθον
στιχ-	ε		ἔστιχον
δοκ-	ε		ἔδοξα
γαμ-	ε		ἔγημα

"Stems Which Lengthen the Vowel in the Present", in Curtius, Georg. The Greek Verb: Its Structure and Development. Translated by Augustus S Wilkins and E. B England. London: J. Murray, 1880.
"The E-Class and the Related Formations", in Curtius, Georg. The Greek Verb: Its Structure and Development. Translated by Augustus S Wilkins and E. B England. London: J. Murray, 1880.
„Verben, deren reinem Stamme im Praes. und Impf. ε zugefügt ist", in Kühner, Raphael. Ausführliche Grammatik Der Griechischen Sprache. Edited by Friedrich Blass and Bernhard Gerth. 3. Aufl. ed. Hannover: Hahnsche Buchhandlung, 1890, vol 1 part 2, p. 179

Τ tau progressive marker

Some Ancient Greek verbs have a tau added to the root in the progressive tenses. Most of these are best understood as a reflex of roots ending in a labial plus the yod/iota progressive marker.

stem/root	marker	progressive	aorist
βλαβ-	y		ἔβλαβον
καλυβ-	y		ἐκάλυψα
κλεπ-	y		ἔκλεψα
σκεπ-	y		ἐσκεψάμην
ἅφ-	y		ἧψα
θαφ-	y		ἔθαψα

Sihler, Andrew L. New Comparative Grammar of Greek and Latin, Oxford, New York: Oxford University Press p. 515, section 465.1
Obsolete: "The T-Class", in Curtius, Georg. The Greek Verb: Its Structure and Development. Translated by Augustus S Wilkins and E. B England. London: J. Murray, 1880.

Reduplication

Reduplication is a hallmark of the perfect aspect system in both Latin and Ancient Greek, but some Ancient Greek verbs reduplicate the root in the progressive tenses. Reduplication can cause a lot of sound changes, including loss of aspiration, or loss of a vowel.

stem/root	marker	progressive	aorist
δρα-	δι		ἀπέδραν
δυ-	δι		ἔδυσα
γνω-	γι		ἔγνων
γεν-	γι		ἐγενόμην
βρω-	βι		ἔβρων
τειν-	τι		ἐτεινάμην
δά-	δι		ἐδίδαξα
μνα-	μι		ἔμνησα