Definition of: synizesis

(sin′ə·zē′sis) noun
1. In Greek prosody, the union in pronunciation of two vowels that cannot form a diphthong, so as to pass for one syllable: differing from contraction in not being made in the written word, but only in pronunciation. Compare SYNERESIS.
2. Biol. The contractile massing of the chromatin during meiotic cell division: associated with synapsis.
3. Med. Contraction of the pupil of the eye. Also syn′e·zi′sis (-zī′sis). [<LL <Gk. synizēsis <synizanein sink down <syn- together + izanein settle down, sit <izein seat, sit]