off key

adjective

1. deviating from the correct tone or pitch; out of tune.
2. Informal. somewhat irregular, abnormal, or incongruous.

adjective, adverb (off-key when prenominal)

1. music
   1. not in the correct key
   2. out of tune
2. out of keeping; discordant

adj.1920, from off (adv.) + musical sense of key (n.1). Figurative sense is from 1943.