Definition of "low-key"

The classic example of low key photography is a black cat in a coal cellar. […] The most popular use of low-key photography is in making portraits of celebrities or theatrical personalities. These people demand either dignity or drama, and this type of lightning is appropriate for both.

1942 November, Victor Keppler, “Key to Good Pictures”, in Popular Photography, page 98

For a low-key, somewhat predictable meal, dinner at Basem's offers good value.

1984 November 18, Patricia Brooks, “Specials Best at Low-Key Spot”, in The New York Times‎

From the Samba band and colourfully-clad dancers that made a lap of Wembley before kick-off - even prompting some neat moves from one or two Brazilian journalists - to the roars of delight every time Neymar got on the ball, it was still a night that contained entertainment despite the increasingly low-key fare on the pitch.

2017 November 14, Phil McNulty, “England 0-0 Brazil”, in BBC News‎

The relatively low-key opening was attended by Metro Mayor Steve Rotheram, who declared "We have a brand-new station serviced with brand-new lines and new publicly owned trains.

2023 October 18, Chris Howe, “Network News: Headbolt Lane station opens on Merseyrail”, in RAIL, number 994, page 22

I'm low key salty about the way that nigga did you but it seems like he still cares about you.

2015, Lady Onyxx, Started From The Top Now I'm Here 3, page 81

Before I open the messages, I disable the activity notification so no one will know I'm low-key obsessed with a party I didn't get to attend.

2018, Rachel Vincent, Strange New World