An isolating language is a type of language with a morpheme per word ratio close to one, and with no inflectional morphology whatsoever. In the extreme case, each word contains a single morpheme. Examples of widely spoken isolating languages are Yoruba in West Africa and Vietnamese (especially its colloquial register) in Southeast Asia.

A closely related concept is that of an analytic language, which uses unbound morphemes or syntactical constructions to indicate grammatical relationships. Isolating and analytic languages tend to overlap in linguistic scholarship.

Isolating languages contrast with synthetic languages, also called inflectional languages where words often consist of multiple morphemes. That linguistic classification is subdivided into the classifications fusional, agglutinative, and polysynthetic, which are based on how the morphemes are combined.