‖n.; pl. Cirri [ L., lock, curl, ringlet. ] [ Also written cirrhus. ] [ 1913 Webster ] 1. (Bot.) A tendril or clasper. [ 1913 Webster ] 2. (Zool.) (a) A soft tactile appendage of the mantle of many Mollusca, and of the parapodia of Annelida. Those near the head of annelids are Tentacular cirri; those of the last segment are caudal cirri. (b) The jointed, leglike organs of Cirripedia. See Annelida, and Polychæta. [ 1913 Webster ] ☞ In some of the inferior animals the cirri aid in locomotion; in others they are used in feeding; in the Annelida they are mostly organs of touch. Some cirri are branchial in function. [ 1913 Webster ] 3. (Zool.) The external male organ of trematodes and some other worms, and of certain Mollusca. [ 1913 Webster ] 4. (Meteor.) See under Cloud. [ 1913 Webster ] | 