ˈhīdəd.ə̇d, -īdətə̇d noun
Etymology: probably from (assumed) New Latin hydatid-, hydatis, from Greek, watery vesicle, from hydat-, hydōr water
1. also hydatid cyst : a larval tapeworm typically comprising a fluid-filled sac from the inner walls of which develop daughter cysts and scolices but occasionally forming an uncircumscribed proliferating spongy mass that actively invades and metastasizes in the host's tissues — see echinococcus ; compare coenurus , cysticercoid , cysticercus
2.
a. : an abnormal cyst or cystic structure ; especially : hydatidiform mole
b. : hydatid disease