nut

The definition of a nut is a dry fruit with one seed or kernel.

(noun)

An example of a nut is an almond.

The definition of a nut is a small metal or wood block with a threaded hole in the middle.

(noun)

An example of a nut is how you would keep a metal screw from popping out of its hole.

Nut is a slang term for a crazy or eccentric person or a fan of someone or something.

(noun)

An example of a nut is a person who yells at the top of their lungs for no reason in public places.
An example of a nut is a nut about antiques, one who loves antiques.

See nut in Webster's New World College Dictionary

noun

the dry, one-seeded fruit of any of various trees or shrubs, consisting of a kernel, often edible, in a hard and woody or tough and leathery shell, more or less separable from the seed itself, as the walnut, pecan, chestnut, acorn, etc.
the kernel, or meat, of such a fruit
loosely any hard-shell fruit that will keep more or less indefinitely, as a peanut, almond, etc.
a small block, usually of metal, with a threaded hole through the center, for screwing onto a bolt, screw, etc.
1. a ridge of ebony or other hard material at the top of the fingerboard of a stringed instrument, over which the strings pass
2. the small knob at the end of a violin bow, for tightening or loosening the hairs
Informal the initial cost of an undertaking, or the amount of money it is necessary to take in before a profit is realized on it
Slang
1. the head
2. the testicles: a vulgar usage
Slang
1. a foolish, crazy, or eccentric person
2. a devotee; fan
Printing en (sense )

Origin: ME nutte < OE hnutu, akin to Ger nuss < IE *kneu-, lump, nut (< base *ken-, to squeeze together) > L nux, MIr cnū

intransitive verb nutted, nutting

to hunt for or gather nuts

See nut in American Heritage Dictionary 4

noun

a. An indehiscent, hard-shelled, one-loculated, one-seeded fruit, such as an acorn or hazelnut.
b. A seed borne within a fruit having a hard shell, as in the peanut, almond, or walnut.
c. The kernel of any of these.
Slang
a. A crazy or eccentric person.
b. An enthusiast; a buff: a movie nut.
Informal A difficult endeavor or problem: Painting the closet was a tough nut to crack.
Slang The human head.
Music
a. A ridge of wood at the top of the fingerboard or neck of a stringed instrument, over which the strings pass.
b. A device at the lower end of the bow for a stringed instrument, used for tightening the hairs.
A small block of metal or wood with a central, threaded hole that is designed to fit around and secure a bolt or screw.
Slang
a. The cost of launching a business venture.
b. The operating expenses of a theater, theatrical production, or similar enterprise: “The [theater] has simply failed to attract enough paying customers per week to meet its nut” (Variety).
Vulgar Slang A testicle.