structural:scholar_edition, linguistic:voice_change
Augment

The indicative of past tenses adds (conceptually, at least) a prefix /e-/, called the augment. This was probably originally a separate word, meaning something like "then", added because tenses in PIE had primarily aspectual meaning. The augment is added to the indicative of the aorist, imperfect, and pluperfect, but not to any of the other forms of the aorist (no other forms of the imperfect and pluperfect exist).

The two kinds of augment in Greek are syllabic and quantitative. The syllabic augment is added to stems beginning with consonants, and simply prefixes e (stems beginning with r, however, add er). The quantitative augment is added to stems beginning with vowels, and involves lengthening the vowel:

Some verbs augment irregularly; the most common variation is e → ei. The irregularity can be explained diachronically by the loss of s between vowels, or that of the letter w, which affected the augment when it was word-initial.In verbs with a preposition as a prefix, the augment is placed not at the start of the word, but between the preposition and the original verb. For example, προσ(-)βάλλω (I attack) goes to προσ έ βαλoν in the aorist. However compound verbs consisting of a prefix that is not a preposition retain the augment at the start of the word: αὐτο(-)μολῶ goes to ηὐ τομόλησα in the aorist.

Following Homer 's practice, the augment is sometimes not made in poetry, especially epic poetry.

The augment sometimes substitutes for reduplication; see below.