Real Dictionary

N.U.T. in American English
abbreviation: National Union of Teachers

nut
countable noun: A nut is a thick metal ring which you screw onto a metal rod called a bolt. Nuts and bolts are used to hold things such as pieces of machinery together.
countable noun: The firm shelled fruit of some trees and bushes are called nuts. Some nuts can be eaten.

nut in American English
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.
noun: a dry fruit consisting of an edible kernel or meat enclosed in a woody or leathery shell
noun: the goddess of the sky, sometimes shown as a cow bearing Ra on her back and the stars on her underside

nut in British English
abbreviation for: National Union of Teachers
noun: a dry one-seeded indehiscent fruit that usually possesses a woody wall
verb: to gather nuts

nut in Mechanical Engineering
noun: A nut is a small square or hexagonal block with a threaded hole through the middle for screwing on the end of a bolt.