cirrus

noun5

1. •
   [before a noun] A principal high-level type of cloud, typically composed of thin, delicate, white filaments or wisps, or narrow bands.

   • He looked at the sky and saw the white cumulus built like friendly piles of ice cream and high above where the thin feathers of the cirrus against the high September sky. — 1952
2. •
   A thin tendril-like appendage, such as a barbel (“whisker-like sensory organ around the mouth”) of some fish, a cilium of some species of protists, or a foot of some crustaceans of the infraclass Cirripedia.

   • Each foot is divided into two parts, one dorsal, the other ventral, and each part has a bundle of subulate bristles and a cirrus. — 1828
3. •
   Synonym of tendril (“a thin, spirally coiling stem that attaches a plant to its support”).

   • Cirri are taken for those fine Strings, or Hairs, by vvhich some Plants fasten themselves, in order to their Support in creeping along; as Ivy, &c. — 1706
4. •
   (no longer used) A long, thin, wirelike tail feather.
5. •
   (no longer used) A tuft of ornamental feathers.