Dictionary.net

p[=i]-r[=o]-s[=o]'ma, n. a genus of compound Tunicates, with brilliant phosphorescence, inhabiting the Mediterranean and the Atlantic--fire-flames. [Gr. pyr, fire, s[=o]ma, body.]

[Greek] A genus of Protozoa. P. bigeminum, a species producing Texas cattle-fever; by some identified with Babesia bovis.

A genus of microorganisms belonging to the Protozoa.