Green’s Dictionary of Slang

music n.

also musick

1. [17C–early 19C] (UK Und.) a term used among highwaymen to signify that an individual is a friend and must not be hindered on their journey; usu. in phr. the music’s paid.

2. [late 18C–early 19C] (Irish) the ‘tail’ of a coin [the ‘tail’ or reverse side of an Irish halfpenny or farthing bore the image of a harp].

3. [mid-19C] (UK Und.) a verdict of ‘not guilty’.

4. [mid-19C+] (US) amusement, fun, lively speech.

5. [mid-19C+] (US) gunfire.

6. [late 19C–1970s] talking, esp. complaints or nagging.

In phrases

face the music (v.) [mid-19C+]

1. to deal stoically with a problem or difficult situation.

2. to take one’s punishment.

read the music (v.)

[1940s] (US gay/prison) to know what is going on.

SE in slang uses

In compounds

music box (n.)

1. [mid-19C–1940s] a piano.

2. [1940s] a guitar.

music-duffing (n.) [duff v.1 (3)]

[1910s–20s] the reconditioning of musical instruments.