A great many Greek verbs have a stem ending in a short vowel — α, ε or ο. When the connecting vowel of the present or imperfect is added to it, the two vowels run together into a long vowel or a diphthong. That is contraction, and the verbs are called contract verbs.
They are not a curiosity. 513 of the 1,853 verb lemmas in the New Testament are contract verbs, and they account for 5,901 of its 28,056 verb forms — one verb in five. ποιέω alone occurs 568 times.
What contraction does
The rules are real but there is no point memorising them; you want to be able to work backwards from what is on the page. The useful half:
| Stem vowel | Meets | Gives |
|---|---|---|
| ε | ε | ει |
| ε | ο | ου |
| α | an e-sound | α |
| α | an o-sound | ω |
| ο | a long vowel | ω |
| ο | a short vowel or ου | ου |
What every one of them has in common is that a long vowel or a diphthong appears where you expected the ordinary ending. That is the signal. When a present tense verb has -εῖ, -οῦ, -ῶ or -ᾷ where you were expecting -ε or -ο, you are looking at a contract verb.
The three types in the present
| ε: ποιέω | α: ἀγαπάω | |
|---|---|---|
| 1 sg | ποιῶ | ἀγαπῶ |
| 2 sg | ποιεῖς | ἀγαπᾷς |
| 3 sg | ποιεῖ | ἀγαπᾷ |
| 1 pl | ποιοῦμεν | ἀγαπῶμεν |
| 2 pl | ποιεῖτε | ἀγαπᾶτε |
| 3 pl | ποιοῦσιν | ἀγαπῶσιν |
Every form in that table occurs in the New Testament. Note that both first person singulars are -ῶ: contraction wipes out the difference between the types in some slots, and the lexicon has to tell you which verb you have.
The ε type is much the biggest — 334 lemmas against 91 for α — so if you are guessing, guess ε.
The ο type is rarer than it looks
Textbooks give the ο contraction equal billing with the other two. The text does not.
There are thirty ο-contract present active indicatives in the whole New Testament, spread across twenty-two different forms. No single verb of that type gives you a full paradigm to meet.
οὐ ζηλοῖ ἡ ἀγάπη, οὐ περπερεύεται, οὐ φυσιοῦται
"Love does not envy, does not boast, is not puffed up." ζηλοῖ is ζηλο- plus -ει, and φυσιοῦται is φυσιο- plus -εται.
οὐ τὸ εἰσερχόμενον εἰς τὸ στόμα κοινοῖ τὸν ἄνθρωπον
"It is not what goes into the mouth that defiles a person." κοινοῖ, six occurrences, is the commonest of the thirty. Recognise the -οῖ and -οῦ shapes and spend the time elsewhere.
Outside the present, contraction disappears
This is the good news, and it is most of why contract verbs are less trouble than they look.
Contraction only happens where a vowel meets a vowel. In every tense outside the present and imperfect, the ending begins with a consonant — σ, κ, θ — so nothing contracts. Instead the stem vowel lengthens: α and ε usually become η, and ο becomes ω. A few do not: καλέω and τελέω keep their short ε (ἐκάλεσεν, ἐτέλεσεν), and κοπιάω and πεινάω keep their α (ἐκοπίασα, ἐπείνασεν).
So ποιέω gives ἐποίησεν (75 occurrences) and ποιήσει; ἀγαπάω gives ἠγάπησεν and ἀγαπήσει; πληρόω gives ἐπλήρωσεν. Once you see that η or ω before the tense marker, the verb behaves exactly like λύω.
Which means the whole of the difficulty is confined to two tenses.
Liquid verbs: a future with no σ
A different irregularity, and a smaller one. Verbs whose stem ends in λ, μ, ν or ρ — the "liquid" consonants — will not take a σ cleanly in the future.
What happens instead is that an ε slips in, the σ drops out between the two vowels, and the ε contracts with the ending. Schematically: μενσω would give μενῶ, the future of μένω. The intermediate spellings are a way of seeing the form, not words anyone wrote.
So a liquid future looks like a contract present, and that is the trap.
| Present | Future | Attested as |
|---|---|---|
| μένω | μενῶ | μενεῖ, μενεῖτε |
| ἀποστέλλω | ἀποστελῶ | ἀποστελεῖ |
| ἐγείρω | ἐγερῶ | ἐγερεῖ |
| κρίνω | κρινῶ | κρινεῖ |
| ἀποκτείνω | ἀποκτενῶ | ἀποκτενοῦσιν |
κρίνει is "he judges"; κρινεῖ is "he will judge". One accent apart, and the tense is the whole difference.
Liquid aorists: the σ goes, the stem stretches
The same consonants cause the same trouble in the aorist, and Greek solves it the same way: the σ of σα drops, and the stem lengthens to compensate.
μένω gives ἔμεινεν · ἀποστέλλω gives ἀπέστειλεν (38 occurrences) · ἐγείρω gives ἤγειρεν (21) · αἴρω gives ἦρεν · κρίνω gives ἔκρινεν.
These are sometimes called asigmatic aorists, because they have no σ. The augment is still there, the endings are the ordinary first aorist ones, and only the σ is missing — so if a form looks like a first aorist with a piece knocked out, this is why.
What to watch for
Contraction is confined to the present and imperfect. Everywhere else the stem vowel usually just lengthens and the verb is regular.
A long vowel or diphthong where you expected a short one is the signal. -εῖ, -οῦ, -ῶ, -ᾷ.
κρίνει and κρινεῖ differ by an accent, and by a tense. This is the place in the course where accents finally have to be read.
And a lexicon lists the uncontracted form — ἀγαπάω, ποιέω — which is a form you will never meet on a page. That is not a mistake in the lexicon; it is how the verb is named.