play by ear

play something by ear

1. to deal with a situation as it develops and without a plan. I'm not sure if I can go bowling or not, I'll just have to play it by ear.

Usage notes: sometimes used with other verbs: I write by ear, and rarely with any exact notion of how I want it to come out.

2. to play a piece of music after hearing it and without written music. My brother can play anything on the piano by ear.

See also: ear, play