(Science: zoology) 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 amoebiform.
Synonym: Gregarinida, and Gregarinaria.
Origin: NL, fr. Gregarina the typical genus, fr. L. Gregarius. See gregarious.