the blues
Etymology
EnglishAmerican English
The phrase 'the blues' for sadness comes from the 18th-century expression 'blue devils', meaning a feeling of melancholy or low spirits. The colour blue has been linked to sadness since at least the 1300s, when Chaucer wrote of 'blue' as a colour of woe. By the 1800s, 'the blues' was used in everyday American English to describe a passing mood of sadness. Decades later, the African-American musical genre blues took its name from the same emotional state.