‖n. pl. [ NL., from Gr. &unr_; indiscernible; 'a priv. + &unr_; to distinguish. ] (Zool.) The lowest groups of animals, in which no nervous system has been observed. [ 1913 Webster ]

a. (Zool.) Of or pertaining to the Acrita. -- n. An individual of the Acrita. [ 1913 Webster ]