The Klingon language is the constructed language spoken by the fictional Klingons in the Star Trek universe. Described in the 1984 book The Klingon Dictionary by Marc Okrand and deliberately designed to sound "alien", it has a number of typologically uncommon features. The language's basic sound, along with a few words, was first devised by actor James Doohan ("Scotty") for Star Trek: The Motion Picture. That film marked the first time the language had been heard on screen. In all previous appearances, Klingons spoke in English. Klingon was subsequently developed by Okrand into a full-fledged language.
A small number of people are capable of conversing in Klingon. Its vocabulary, heavily centered on Star Trek-Klingon concepts such as spacecraft or warfare, can sometimes make it cumbersome for everyday use.