From Longman Dictionary of Contemporary Englishlow-keyˌlow-ˈkey adjective UNIMPORTANTnot intended to attract a lot of attention to an event, subject, or thing They want the funeral to be as low-key as possible. a low-key military operation
Examples from the Corpus
low-key• On the first day of the blockade, policing was low-key.• But the campaigns have been very amateurish and low-key and many of the younger people are not interested.• This year's campaign was low-key and quiet.• a low-key approach to management• Such a low-key comment is not what is required by the popular press at the conclusion of a traumatic trial.• In the war against Microsoft, it was a low-key day.• They're low-key, fun and there's no pressure to pair anyone off.• He had an appealing, low-key manner.• He is rueful, polite, mildly disappointed, and afflicted by a low-key melancholy.• It was to hold up any new organizing at all, even on a quiet, low-key scale. 