Definition of cirrus

• n. - A tendril or clasper.
• n. - 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.
• n. - The jointed, leglike organs of Cirripedia. See Annelida, and Polychaeta.
• n. - The external male organ of trematodes and some other worms, and of certain Mollusca.
• n. - See under Cloud.