seta

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

• noun A stiff hair, bristle, or bristlelike process or part on an organism, especially an invertebrate.
• noun The stalk of a moss or liverwort capsule.

from The Century Dictionary.

• noun In zoology and anatomy, a bristle; a chæta; a stiff, stout hair; a fine, slender spine or prickle; any setaceous appendage.
• noun In botany, a bristle of any sort; a stiff hair; a slender, straight prickle; also, the stalk that supports the theca, capsule, or sporangium of mosses.

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

• noun (Biol.) Any slender, more or less rigid, bristlelike organ or part; as the hairs of a caterpillar, the slender spines of a crustacean, the hairlike processes of a protozoan, the bristles or stiff hairs on the leaves of some plants, or the pedicel of the capsule of a moss.
• noun One of the movable chitinous spines or hooks of an annelid. They usually arise in clusters from muscular capsules, and are used in locomotion and for defense. They are very diverse in form.
• noun One of the spinelike feathers at the base of the bill of certain birds.

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

• noun A bristle or hair
• noun botany The stalk of a moss sporangium, or occasionally in a liverwort.

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

• noun stalk of a moss capsule
• noun a stiff hair or bristle