AUGMENT.

English has nothing comparable to this.

In certain forms a prefix is added tot the stem, called “augment(um)”

The prefix consists of either a precursory syllable ἐ-, or lengthening of an initial vowel.

1) The first kind is called “augmentum syllabicum” and is applied to all stems beginning with a consonant, and also a very few beginning with a vowel. [Three verbs distinguish thermselves from the common herd by (sometimes) taking ἠ- instead of ἐ-: βούλομαι > ἠβουλ--, δύναμαι> ἠδυν--, μέλλω> ἠμελ--]

2) The second kind is called “augmentum temporale” and is applied in stems beginning with a short vowel. Stems beginning in ἰ- or ὐ- have no visible augmentation.

3) Thirdly – in very few verbs - there is an augmentation consisting of both syllabicum and temporale; this we call augmentum duplex.

Forms that get one of these additions are: 1) all past-indicatives [durative past indicative is traditionally named "imperfect"], 2) all perfect forms of “non-reduplicant” stems (see page on REDUPLICATION).

Examples and further detail:

1) augm. syllabicum: stem λυ-, ao A pa-ind 1^st sg: ἔλυσα. [Stems with initial ῥ- show a redoubling of the ρ in augmented forms: stem ῥηγ-, du A pa-ind 1^st sg ἔρρηγνυν; older texts often print this and other forms of this kind ἔῤῥηγνυν].

2) augm. temporale: stem ὀρυγ-, du A pa-ind 1^st sg ὤρυσσον.

Which form the lengthening actually takes in all occurring cases may be derived from this list (ordered alphabetically by augmented form):

3) augm. duplex: stem οἰγ- , du A pa-ind 1^st sg: ἔῳγνυν.

                                                                                               εα-, εη- < α-                                                                                               εω- <  ο -                                                                                                  εῳ- < οι-

(No spirits have been placed, because the lists are valid for both lenis and asper).              

[In Epic (Homer) the augment is not compulsory in past indicatives.
In other Ionic (Herodotus) augmentum temporale is not compulsory in any form.]

 Greek has many compound verbs. These may be divided into two groups:

1) Those compounded with a word that is otherwise in use as a preposition (comparable to English forgive), such as ἀποβάλλω,

2) Those compounded with other elements, chiefly ἀ-, εὐ-, δυσ-.

For augmentation, the second kind are treated like any other verb,
but in the first kind the augmentation is applied as follows: first the compounding particle is separated from the verb proper, then the verb proper is augmented as described above and then the particle is reattached to the form. [εὐ- & δυσ- are taken “as prepositions” when followed by a vowel: εὐηργέτουν from εὐεργετέω]

This is only the principle; for further detail one is referred to the page on COMPOUND VERBS.

[N.B. These pages are designed to get you through your first readings. It may be years before you encounter anything that does not conform, but don’t be surprised at slight deviations.]