Correption

In Latin and Greek poetry, correption is the shortening of a long vowel at the end of one word before a vowel at the beginning of the next. Vowels next to each other in neighboring words are in hiatus.
Homer uses correption in dactylic hexameter:

Ἄνδρα μοι ἔννεπε, Μοῦσα, πολύτροπον, ὃς μάλα πολλὰ

πλάγχθη, ἐπεὶ Τροίης ἱερὸν πτολίεθρον ἔπερσε·
— Odyssey

Tell me, O Muse, of the man of many devices, who wandered full

many ways after he had sacked the sacred citadel of Troy.
—
Here the sequence η ε in bold must be pronounced as ε ε to preserve the long—short—short syllable weight sequence of a dactyl. Thus, 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", exhibiting Attic correption, or as "δάκ ρυ", in keeping with the conventions of Homeric verse.