zygospore n 1: a plant spore formed by two similar sexual cells
Zygospore \Zyg"o*spore\, n. [Gr. zygo`n a yoke + E. spore.] (Bot.) (a) Same as {Zygosperm}. (b) A spore formed by the union of several zoospores; -- called also {zygozoospore}. [1913 Webster]