The Collaborative International Dictionary of English v.0.48:
Nut \Nut\ (n[u^]t), n. [OE. nute, note, AS. hnutu; akin to D.
noot, G. nuss, OHG. nuz, Icel. hnot, Sw. n["o]t, Dan.
1. (Bot.) The fruit of certain trees and shrubs (as of the
almond, walnut, hickory, beech, filbert, etc.), consisting
of a hard and indehiscent shell inclosing a kernel.
2. A perforated block (usually a small piece of metal),
provided with an internal or female screw thread, used on
a bolt, or screw, for tightening or holding something, or
for transmitting motion. See Illust. of 1st Bolt.
3. The tumbler of a gunlock. --Knight.
4. (Naut.) A projection on each side of the shank of an
anchor, to secure the stock in place.
5. pl. Testicles. [vulgar slang]
Check nut, Jam nut, Lock nut, a nut which is screwed up
tightly against another nut on the same bolt or screw, in
order to prevent accidental unscrewing of the first nut.
Nut buoy. See under Buoy.
Nut coal, screened coal of a size smaller than stove coal
and larger than pea coal; -- called also chestnut coal.
Nut crab (Zool.), any leucosoid crab of the genus Ebalia
as, Ebalia tuberosa of Europe.
Nut grass (Bot.), See nut grass in the vocabulary.
Nut lock, a device, as a metal plate bent up at the
corners, to prevent a nut from becoming unscrewed, as by
Nut pine. (Bot.) See under Pine.
Nut rush (Bot.), a genus of cyperaceous plants (Scleria)
having a hard bony achene. Several species are found in
the United States and many more in tropical regions.
Nut tree, a tree that bears nuts.
Nut weevil (Zool.), any species of weevils of the genus
Balaninus and other allied genera, which in the larval
state live in nuts.