ge·​lid·​i·​um | \ jəˈlidēəm\

Definition of gelidium

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 plural -s : any alga of the genus Gelidium

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History and Etymology for gelidium

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

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