tendril

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A twisting, threadlike structure by which a twining plant, such as a grape or cucumber, grasps an object or a plant for support.
2. n. Something, such as a ringlet of hair, that is long, slender, and curling.

Century Dictionary and Cyclopedia

1. n. In botany, a filiform leafless plant-organ that attaches itself to another body for the purpose of support. Morphologically, a tendril may be a modified stem, as in the vine and Virginia creeper; a modified branch, as in the passion-flower; a petiole, as in Lathyrus Aphaca; a stipule, or, as in Smilax, a pair of stipules; or a leaflet of a compound leaf, as in the pea and vetch. The morphology of the tendrils in the Cucurbitaceæ is still open to question; by Braun and Wydler they are regarded as simple leaves of which the ribs are the branches of the tendril (a view adopted also by Eichler), but Naudin regards the main tendril as cauline and the branches as leaves. Tendrils are usually found on those plants which are too weak in the stem to enable them to grow erect; they twist themselves, usually in a spiral form, around other plants or neighboring bodies, and the plants on which they grow are thus enabled to elevate themselves. See cuts under cirrus, creeper, Lathyrus, passion-flower, and Smilax.
2. Climbing as a tendril, or as by a tendril.

Wiktionary

1. n. botany A thin, spirally coiling stem that attaches a plant to its support.
2. n. zoology A hair-like tentacle.

GNU Webster's 1913

1. n. (Bot.) A slender, leafless portion of a plant by which it becomes attached to a supporting body, after which the tendril usually contracts by coiling spirally.
2. adj. rare Clasping; climbing as a tendril.

WordNet 3.0

1. n. slender stem-like structure by which some twining plants attach themselves to an object for support