The Collaborative International Dictionary
Zygosis
Zygosis \Zy*go"sis\, n. [NL., fr. Gr. ? balancing, fr. zygo`n yoke.] (Biol.) The process of the merging of two gametes. Same as Conjugation.
Wiktionary
zygosis
n. (context biology English) The union of gametes to form a zygote; conjugation.