The Klingon language is the constructed language spoken by a fictional alien race called the Klingons, in the Star Trek universe.

A constructed language is a language whose phonology, grammar, and vocabulary, instead of having developed naturally, are consciously devised for some purpose, which may include being devised for a work of fiction. A constructed language may also be referred to as an artificial, planned or invented language, or a fictional language. Planned languages are languages that have been purposefully designed; they are the result of deliberate, controlling intervention and are thus of a form of language planning.