In Latin and Greek poetry, correption ( , "a shortening") is the shortening of a long vowel at the end of one word before a vowel at the beginning of the next.
Homer uses correption in dactylic hexameter:
— Odyssey 1.1-2 Tell me, O Muse, of the man of many devices, who wandered fullmany ways after he had sacked the sacred citadel of Troy.— translation by A.T. Murray
Here in the first line the οι diphthong in the second word "μοι" would normally be a long vowel and thus create a long syllable, but because the next word begins with a vowel, the οι diphthong suffers correption, in the form of a partial ellision whereby its long syllable is reduced to a short one. Similarly, in the second line the sequence η ε (in bold print) must be pronounced as ε ε to preserve the long—short—short syllable weight sequence of a dactyl. The scansion of the second line is thus:
Attic
Typically, in Homeric meter, a syllable is scanned long or "closed" when a vowel is followed by two or more consonants. However, in Attic Greek, a short vowel followed by a plosive and a liquid consonant or nasal stop remains a short or "open" syllable. This is called Attic correption, sometime known by its Latin name correptio Attica.
Therefore, the first syllable of a word like δᾰ́κρυ could be scanned as "δά κρυ" (open/short), exhibiting Attic correption, or as "δάκ ρυ" (closed/long), in keeping with the conventions of Homeric verse.
See also Metaplasm Hiatus Synalepha
References