LernaeaceaLer`n[ae]*a"ce*a\ (l[~e]r`n[-e]*[=a]"sh[-e]*[.a]), n. pl. [NL. See Lern[ae]a.] (Zo["o]l.) A suborder of copepod Crustacea, including a large number of remarkable forms, mostly parasitic on fishes. The young, however, are active and swim freely. See Illustration in Appendix.