A quiet period after a party; a post-rave gathering that features slow music and a calming ambience; soothing, hypnotic music. adj. Also: chill-out, chill out.
Like so many pop trends, "chillout" started as one thing and ended up quite another.
In the beginning, the term was used by rave aficionados for the soft and airy records they played after a long, mind-altering night of dancing. At early-morning "after-parties," friends would recover from the hard beats of electronica (and the disorienting effects of Ecstasy) with the quiet balm of ambient music.
Who would have thought a term coined for such an underground and illicit ritual would one day morph into a TV-driven, mass-market phenomenon? At the moment, scores of "chillout" albums clog record racks, each sporting a sanitized twist on the form and its own lifestyle-enhancing promise.
Jim Farber, "The new easy listening," Daily News, April 28, 2002
Konspiracy Very funky club run by the posse who used to operate the Kitchen, Manchester's late-night watering hole. Sat is the day: all four rooms are open and the club is firing; the Jam MCs, the main DJs; Spice, ambient DJs, provide a chill-out room.
James Style, "James Style selects the freshest and funkiest in nightlife up and down the country," The Independent, May 23, 1990
The verb chill out, meaning to calm down, to relax, entered the slang lexicon in the early 1980s, but is by now relatively mainstream. (Older non-hipsters mostly use it ironically.) In the 90s, "chill out" morphed into both a noun (see the citation above) and an adjective, shown in the earliest citation.