a dry fruit consisting of an edible kernel or meat enclosed in a woody or leathery shell.

the kernel itself.

Botany . a hard, indehiscent, one-seeded fruit, as the chestnut or the acorn.

any of various devices or ornaments resembling a nut.

a block, usually of metal and generally square or hexagonal, perforated with a threaded hole so that it can be screwed down on a bolt to hold together objects through which the bolt passes.

Slang . the head.

Slang .

a person who is very enthusiastic about something; buff; enthusiast; devotee

He's a real circus nut.

an extremely concerned or zealous person

My boss is a nut on double-checking everything.

Slang .

a foolish, silly, or eccentric person.

Offensive . an insane person; psychotic.

Slang

Vulgar a testis.

Informal .

the operating expenses, usually figured weekly, of a theatrical production or other commercial enterprise; a break-even point.

the total cost of producing a theatrical production or of forming and opening any new business venture.

Music . (in instruments of the violin family)

the ledge, as of ebony, at the upper end of the fingerboard, over which the strings pass.

the movable piece at the lower end of the bow, by means of which the hairs may be slackened or tightened.

Printing . en ( def. 2 ) .

to seek for or gather nuts

to go nutting in late autumn.

from soup to nuts. soup ( def. 7 ) .

hard nut to crack

a problem difficult to solve; a formidable undertaking.

a person difficult to know, understand, or convince. Also, tough nut to crack.

off one's nut

Slang .

Sometimes Offensive . foolish, silly, or insane.

confused; unreasonable.

mistaken or wrong

You're off your nut if you think such a plan can succeed.

noun

sane person

noun

achene , caryopsis , kernel , stone , utricle , bedlamite , bigot , crackpot , crank , dement , eccentric , fanatic , fiend , freak , harebrain , loony * , lunatic , maniac , non compos mentis , screwball * , zealot , crazy , bug , devotee , noddle , pate , poll , acorn , almond , betel , bur , cashew , core , filbert , hazel , hickory , kola , peanut , pecan , pistachio