English

low-key

From low + key.

A compound of low + key

Proto-Indo-European *legʰ- ‘to lie’

…

Proto-Germanic *ligjaną ‘to lie’

Proto-Germanic *lēgaz ‘low’

Old Norse lágr

Middle English lāh

English low

Proto-West Germanic *kaiju

Old English cǣġ ‘key’

Middle English keye ‘a key’

English key

Today it means

adj Dark; characterized by dark tones and muted colors.

Language periods are conventional ranges, not dates for this word.