\Ep`i*zo"["o]n\, n.; pl. {Epizoa}. [NL., fr. Gr. 'epi`
upon + ? animal.] (Zo["o]l.)
One of the artificial group of invertebrates of various
kinds, which live parasitically upon the exterior of other
animals; an ectozo["o]n. Among them are the lice, ticks, many
acari, the lerneans, or fish lice, and other crustaceans.