What is "crasis"

Crasis \Cra"sis\ (kr?"s?s), n. [LL., temperament, fr. Gr. ????, fr. ???? to mix.]

1. (Med.) A mixture of constituents, as of the blood; constitution; temperament.

2. (Gram.) A contraction of two vowels (as the final and initial vowels of united words) into one long vowel, or into a diphthong; syn[ae]resis; as, cogo for coago. [1913 Webster] ||

n. 1 (context obsolete English) One's constitution; the balance of humours in a person's body. 2 A mixture or combination. 3 (context linguistics English) The contraction of a vowel or diphthong at the end of a word with a vowel or diphthong at the start of the following word.

Crasis (; from the Greek , "mixing", "blending") is a type of contraction in which two vowels or diphthongs merge into one new vowel or diphthong, making one word out of two. Crasis occurs in Portuguese and Arabic as well as in Ancient Greek for which it was first described.

In some cases, like in the French examples below, crasis involves the grammaticalization of two individual lexical items into one, but in other cases, like in the Greek examples, crasis is the orthographic representation of the encliticization and vowel reduction of one grammatical form with another. The difference between the two is that the Greek examples involve two grammatical words and a single phonological word and the French examples involve a single phonological word and grammatical word.