 Colorless green ideas sleep furiously

"Colorless green ideas sleep furiously" is a famous sentence coined by linguist Noam Chomsky in his 1957 book "Syntactic Structures." The phrase is often cited as an example of a grammatically correct sentence that is semantically nonsensical. The purpose of this sentence was to illustrate the distinction between syntax (the rules that govern sentence structure) and semantics (the meanings of words and sentences).