"Bollocks" is a slang term meaning testicles in British English, but more often used figuratively. It is rarely used in the singular. It has come to mean rubbish or 'Crap' or even used in a similar way to Bullshit, and this usage is international. One of its singular forms is used to describe the malfunction of an operation, or messing up something "Dropping a Bollock".

Perhaps the best-known international use of the term in this sense is in the title of a Sex Pistols album. Testimony in a resulting lawsuit over the "obscene" term demonstrated that in Old English the word referred to a priest, and could also be used to mean "nonsense" (see Never Mind the Bollocks, Here's the Sex Pistols for details). This common usage of the word has come to prominence with the phrase "What a load of bollocks".

Another usage with the opposite meaning is "the dog's bollocks", which fits in with several rhyming reduplications of positive meaning that were popular during the 1920's ("the bee's knees," "the cat's pyjamas"). Another derivation of the meaning "something that is very good", it is based on the notion that a dog's bollocks must taste good, as they spend so much time licking them. In the same vein, the word bollocks can again be used to mean something good when you're talking about a person or object, 'My new car is the bollocks!' or 'That new chef down the road, she's the bollocks!'

Used in the singular to describe being in the nude: "stark bollock naked".

Bollocking refers to a severe telling-off. For example, "The boss gave him a right bollocking."

It is sometimes spelt bollox or bollix, usually by residents of countries other than the British Isles who don't quite understand what it means. Residents of said countries may respond that they consider bollix a separate word which means to make a foolish mistake that detracts from a work in progress: "The project was going well but my boss bollixed it up."

It may also be used to refer to a particularly nasty or awkward person: "he's a right Bollix" [Ireland]