‖n. pl. [ L. piscis a fish. ] 1. (Astron.) (a) The twelfth sign of the zodiac, marked &pisces_; in almanacs. (b) A zodiacal constellation, including the first point of Aries, which is the vernal equinoctial point; the Fish. [ 1913 Webster ]
2. (Zool.) The class of Vertebrata that includes the fishes. The principal divisions are Elasmobranchii, Ganoidei, and Teleostei. [ 1913 Webster ]