out-of-this-world

The phrase "out of this world" is a modern English idiom, originating in the early 20th century. Its literal meaning, describing something originating from beyond Earth, was quickly adopted into figurative use, particularly in American English. The logic of the idiom relies on hyperbole, suggesting that the quality of the thing described is so extraordinary that it cannot be of earthly origin. It evolved from science fiction and aerospace terminology into common colloquial praise, capturing a sense of awe and superlative excellence.

This is a fixed idiomatic phrase functioning as a compound adjective. It is not productively formed from separable morphemes in the context of its modern meaning.