cirrus
cir.rus \'sir-*s\ \'sir-.i-\ n or cir.ri [NL, fr. L, curl] pl 1: TENDRIL 2: a slender usu. flexible animal appendage : as 2a: an arm of a barnacle 2b: a filament of a crinoid 2c: a tactile barbel (as of a fish) 2d: a tuft of hair on the legs or antennae of many insects 2e: a fused group of cilia functioning like a limb on some protozoans 2f: the male copulatory organ of various invertebrate animals 3: a wispy white cloud usu. of minute ice crystals formed at altitudes of 2 0, 000 to 40, 000 feet
Webster's English Dictionary