cirrus

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A high-altitude cloud composed of narrow bands or patches of thin, generally white, fleecy parts.
2. n. Biology A tendril or similar part.
3. n. Biology A slender flexible appendage, such as the fused cilia of certain protozoans.

Century Dictionary and Cyclopedia

1. n. In botany, a tendril; a long thread-like organ by which certain plants climb.
2. n. In zoology: In Cirripedia, one of the curved multiarticulate filaments alternately protruded and retracted with a sweeping motion from the shell or carapace of a cirriped, as an acorn-shell (Balanus) or barnacle (Lepas). They are the thoracic appendages or feet of the animal, each representing an endopodite and an exopodite, borne upon a protopodite. See cut under barnacle.
3. n. In Crinoidea, one of the branched filaments given off from the joints of the stem. See cut under Crinoidea.
4. n. In conchology, one of the cirrose branchiæ of the Cirribranchiata or tooth-shells.
5. n. In ichthyology: One of the cirrose filaments surrounding the mouth of a lancelet. A barbel in sundry fishes.
6. n. In ornithology, a tuft of curly plumes on the head.
7. n. In Vermes, the protrusible cirrose terminal portion of the vas deferens of a trematoid or cestoid worm; a kind of penis.
8. n. One of the filamentous appendages of the parapodia in chætopodous annelids, which may be larger than the parapodia, or even replace them when atrophied.
9. n. In entomology, a tuft of curled hairs such as are often seen on the legs and antennæ of insects.
10. n. Some other cirrose part or organ, as the long flattened modification of ordinary cilia upon the peristomial region of many ciliate Infusoria.
11. n. [capitalized] A genus of mollusks.
12. n. A light fleecy cloud, formed at a great height in the atmosphere. See cloud, 1. Also called curlcloud. Often abbreviated c.
13. n. One of the solid contractile tentacle-like organs on the margin of the me- dusoid of Hydromedusæ. Each cirrus is shorter than the tentacles, is provided with a terminal battery of cnidoblasts, and is perhaps an organ of offense or of defense.

Wiktionary

1. n. botany A tendril.
2. n. zoology A thin tendril-like appendage.
3. n. meteorology A principal high-level cloud type characterised by white, delicate filaments or wisps, of white (or mostly white) patches, or of narrow bands, found at an altitude of above 7000 metres.

GNU Webster's 1913

1. n. (Bot.) A tendril or clasper.
2. 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.
3. n. The jointed, leglike organs of Cirripedia. See Annelida, and Polychæta.
4. n. (Zoöl.) The external male organ of trematodes and some other worms, and of certain Mollusca.
5. n. (Meteor.) See under Cloud.

WordNet 3.0

1. n. a wispy white cloud (usually of fine ice crystals) at a high altitude (4 to 8 miles)
2. n. usually coiled
3. n. a slender flexible animal appendage as on barnacles or crinoids or many insects; often tactile