vocalic reduplication

If a verb begins with a vowel or dipthong, the vowel is lengthened. The vocalic reduplication is identical in form to the augment in the imperfect and aorist (BBG 25.8).

αγαπαω becomes ηγαπηκα

εγγιζω becomes ηγγικεν

If the verb begins with two consonants, then the verb will usually undergo vocalic reduplication and not consonantal reduplication; e.g. γνο-

γινωσκω – εγνωκα