jəˈlidēəm noun
Etymology: New Latin, from Latin gelidus (influenced in meaning by Latin gelare to freeze, congeal) + New Latin -ium; from the fact that the plants are boiled down to make a jelly
1. capitalized : a genus of red algae (family Gelidiaceae) having cartilaginous terete or compressed much-branched fronds and cystocarps immersed in swollen branchlets and being important sources of agar — see gelidiales
2. -s : any alga of the genus Gelidium