1. synizesis (the fusion of two syllables into one without the formation of a recognized diphthong, especially to fit a certain poetic meter) (prosody, phonetics, poetry, rhetoric)

2. synizesis (a dense clumping of chromosomes on one side of the nucleus of a cell, sometimes occurring prior to cell division) (cytology)

3. synizesis (occlusion of the pupil of the eye, resulting in loss of vision) (ophthalmology, pathology, obsolete)