Nemathecium \Nem`a*the"ci*um\ (? or ?), n.; pl. {Nemathecia}.
[NL., fr. Gr. nh^ma a thread + ? a box.] (Bot.)
A peculiar kind of fructification on certain red algae,
consisting of an external mass of filaments at length
separating into tetraspores.
[1913 Webster] Nemathelminthes