cirrus

plural cirri

1. biologySynonym 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, Edward Phillips, compiler, J[ohn] K[ersey the younger], “Cirrus”, in The New World of Words: Or, Universal English Dictionary. […], 6th edition, London: […] J. Phillips, […]; N. Rhodes, […]; and J. Taylor, […], →OCLC, signature [R3], verso, column 1

   Synonyms: tendril

2. biologyA 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, John Stark, “II.—Mollusca. Class IV. Cirripeda. Order II.—Antennatæ.”, in Elements of Natural History, Adapted to the Present State of the Science, […], volume II (Invertebrata, &c.), Edinburgh: Adam Black and John Stark; London: Longman, Rees, Orme, Brown & Green, →OCLC, page 135

   1 more example

   All creatures which have their skins protected, whether by feathers, or shells, or scales, have an exquisite touch in their mouth, or in the appendages which hang from it. Fishes have cirri which hang from their mouth, and these are equivalent to the feelers or tentacula of insects and crustaceans.

   1833, Charles Bell, “The Substitution of Other Organs for the Hand”, in The Hand: Its Mechanism and Vital Endowments as Evincing Design, London: William Pickering, →OCLC, page 130

3. obsoletebiologyA tuft of ornamental feathers.
4. obsoletebiologyA long, thin, wirelike tail feather.
5. attributiveoftenclimatologyA principal high-level type of cloud, typically composed of thin, delicate, white filaments or wisps, or narrow bands.

   The blue sky is glossy and fat with heat, a few thin cirri sheared to blown strands like hair at the rims.

   1996, David Foster Wallace, Infinite Jest […], Boston, Mass.; New York, N.Y.: Little, Brown and Company, →ISBN, page 15

   3 more examples

   [page 99] Cirrus. […] Parallel, flexuous, or diverging fibres, extensible in any or in all directions. […] [page 100] In fair weather, with light variable breezes, the sky is seldom quite clear of small groups of the oblique cirrus, which frequently come on from the leeward, and the direction of their increase is to windward.

   1803 July, Luke Howard, “XVIII. On the Modifications of Clouds, and on the Principles of Their Production, Suspension, and Destruction; being the Substance of an Essay Read before the Askesian Society in the Session 1802–3.”, in Alexander Tilloch, editor, The Philosophical Magazine and Journal: Comprehending the Various Branches of Science, the Liberal and Fine Arts, Agriculture, Manufactures, and Commerce, volume XVI, number 62, London: […] [Richard Taylor] for Alexander Tilloch; and sold by Messrs. Richardson, […], →ISSN, →OCLC, pages 99 and 100

   Cirrus clouds moving from the southwest indicate falling temperature; moving from the northwest they indicate the probability of rising temperature. They are the mares' tales and cattails of sailors' cant. Near the horizon, cirrus clouds may have a stratiform appearance.

   1921, Jacques W[ardlaw] Redway, “The Moisture of the Air: Fog and Cloud”, in Handbook of Meteorology: A Manual for Cooperative Observers and Students, New York, N.Y.: John Wiley & Sons; London; Chapman & Hall, →OCLC, part I (General Principles), page 75

   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 September 1, Ernest Hemingway, The Old Man and the Sea, New York, N.Y.: Charles Scribner’s Sons, →OCLC, page 61

   Synonyms: Ci