Pygidium
Pronunciation : Py*gid"i*um
Part of Speech : n.;
Etymology : [NL., fr. Gr. (Zo?l.)
Definition : Defn: The caudal plate of trilobites, crustacean, and certain insects. See Illust. of Limulus and Trilobite.
pl. Pygidia.
Source : Webster's Unabridged Dictionary, 1913