Entry 1 sense Webster, 1913 Cysticule /(s?s"t?-k?l)/ · Cys·ti·cule · IPA /ˈsɪstɪkjuːl/ 01 n. An appendage of the vestibular ear sac of fishes. 1. An appendage of the vestibular ear sac of fishes.(Anat.)