villus

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

• noun Biology A minute projection arising from a mucous membrane, especially.
• noun One of the numerous vascular projections of the small intestine.
• noun One of the fingerlike projections of the chorion that contribute to the formation of the placenta in mammals.
• noun Botany A fine, hairlike epidermal outgrowth.

from The Century Dictionary.

• noun In anatomy: One of numerous minute vascular projections from the mucous membrane of the intestine, of a conical, cylindric, clubbed, or filiform shape, consisting essentially of a lacteal vessel as a central axis, with an arteriole and a veinlet, inclosed in a layer of epithelium, with the basement membrane and muscular tissue of the mucous membrane, and cellular or reticular tissue.
• noun One of the little vascular tufts or processes of the shaggy chorion of an ovum or embryo, in later stages of development entering into the formation of the fetal part of the placenta. See cut under uterus, Some villiform part or process of various animals. See cut under hydranth.
• noun In botany, one of the long, straight, and soft, hairs which sometimes cover the fruit, flowers, and other parts of plants.

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

• noun (Anat.) One of the minute papillary processes on certain vascular membranes; a villosity.
• noun (Bot.) Fine hairs on plants, resembling the pile of velvet.

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

• noun biology a small projection from a mucous membrane, particularly those found in the intestines

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

• noun a minute hairlike projection on mucous membrane