\\"d8Greg`a*ri"n\"91\, n. pl. [NL., fr. Gregarina
the typical genus, fr. L. gregarius. See {Gregarious}.]
(Zo["o]l.)
An order of Protozoa, allied to the Rhizopoda, and parasitic
in other animals, as in the earthworm, lobster, etc. When
adult, they have a small, wormlike body inclosing a nucleus,
but without external organs; in one of the young stages, they
are am[oe]biform; -- called also {Gregarinida}, and
{Gregarinaria}.