unguis

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

• noun Zoology A nail, claw, or hoof.
• noun Botany The clawlike base of some petals.

from The Century Dictionary.

• noun The horny, nail-like covering of the tip of the bill found in ducks and geese.
• noun A nail, claw, or hoof of any animal.
• noun A measure of length, about half an inch. In anatomy: The human lacrymal bone: so called because it resembles the human finger-nail: more fully called os unguis.
• noun The hippocampus minor, or calcar, of the brain. Also unguis avis, unguis Halleri.
• noun In entomology, one of the curved claws at the extremity of an insect's tarsus.
• noun In botany, the claw or lower contracted part of some petals, by which they are attached to the receptacle, as in the pink, the mustard, Cleome, etc. It is analogous to the petiole of a leaf. Also ungula. See cut under claw.

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

• noun The nail, claw, talon, or hoof of a finger, toe, or other appendage.
• noun (Zoöl.) One of the terminal hooks on the foot of an insect.
• noun (Bot.) The slender base of a petal in some flowers; a claw; called also ungula.

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

• noun zoology The nail, claw, talon, or hoof of a finger, toe, or other appendage.
• noun One of the terminal hooks on the foot of an insect.
• noun botany The slender base of a petal in some flowers; a claw; an ungula.

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

• noun any rigid body structure composed primarily of keratin