uncinus

from The Century Dictionary.

• noun A hook or hooklet; a hamulus; something small, hard, and crooked; specifically, in conchology, one of the uncinal teeth of the radula.
• noun One of the hooked cilia of infusorians.
• noun One of the numerous minute chitinous hooks of the tori of some annelids. See Uncinata.
• noun A weapon used in the eleventh century, resembling a martel-de-fer, but thought to have only one point or edge.

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

• noun (Zoöl.) One of the peculiar minute chitinous hooks found in large numbers in the tori of tubicolous annelids belonging to the Uncinata.

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

• noun meteorology A cloud species which consists of fine hair-like strands, with hooked terminations. Associated only with cirrus formations.
• noun paleontology The curved tip of the hooks associated with belemnite tentacles.