■ noun
1》 a fruit consisting of a hard or tough shell around an edible kernel.
↘the hard kernel of such a fruit.
2》 a small flat piece of metal or other material, typically square or hexagonal, with a threaded hole through it for screwing on to a bolt.
↘the part at the lower end of a violin bow with a screw for adjusting the tension of the hair.
3》 informal a crazy or eccentric person.
↘an obsessive enthusiast or devotee.
4》 informal a person's head.
5》 a small lump of coal.
6》 ( ~s ) vulgar slang a man's testicles.
7》 the fixed ridge on the neck of a stringed instrument over which the strings pass.
■ verb ( ~s , ~ting , ~ted )
1》 Brit. informal butt with one's head.
2》 [usu. as noun ~ting ] archaic gather ~s.
Phrases
do one's ~ Brit. informal be extremely angry or agitated.
~s and bolts informal the basic practical details.
a tough (or hard ) ~ to crack informal a problem or an opponent that is hard to solve or overcome.
use (or take ) a sledgehammer to crack a ~ informal use disproportionately drastic measures to deal with a simple problem.
Origin
OE h~u , of Gmc origin.