cirrus

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A high-altitude cloud composed of narrow bands or patches of thin, generally white, fleecy parts.
• noun A tendril.
• noun A slender flexible appendage, such as a tuft of fused cilia of certain protozoans or one of the feathery appendages of a barnacle.

from The Century Dictionary.

• noun 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.
• noun In botany, a tendril; a long thread-like organ by which certain plants climb.
• noun 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).
• noun In Crinoidea, one of the branched filaments given off from the joints of the stem. See cut under Crinoidea.
• noun In conchology, one of the cirrose branchiæ of the Cirribranchiata or tooth-shells.
• noun In ichthyology: One of the cirrose filaments surrounding the mouth of a lancelet. A barbel in sundry fishes.
• noun In ornithology, a tuft of curly plumes on the head.
• noun In Vermes, the protrusible cirrose terminal portion of the vas deferens of a trematoid or cestoid worm; a kind of penis.
• noun One of the filamentous appendages of the parapodia in chætopodous annelids, which may be larger than the parapodia, or even replace them when atrophied.
• noun In entomology, a tuft of curled hairs such as are often seen on the legs and antennæ of insects.
• noun Some other cirrose part or organ, as the long flattened modification of ordinary cilia upon the peristomial region of many ciliate Infusoria.
• noun [capitalized] A genus of mollusks.
• noun A light fleecy cloud, formed at a great height in the atmosphere. See cloud, 1. Also called curlcloud. Often abbreviated c.

from the GNU version of the Collaborative International Dictionary of English.

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

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun botany A tendril.
• noun zoology A thin tendril-like appendage.
• noun 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.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

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