Webster's Revised Unabridged Dictionary · 1913

Crasis

Crasis (kr?"s?s) , noun

[Late Latin, temperament, from Greek {not transcribed}, from {not transcribed} to mix.]

1.
(Medicine) A mixture of constituents, as of the blood; constitution; temperament.
2.
(Grammar) A contraction of two vowels (as the final and initial vowels of united words) into one long vowel, or into a diphthong; synaresis; as, cogo for coago.