Definition of in or out of key in English:

in (or out of) key

In (or out of) harmony: this vaguely uplifting conclusion is out of key with the body of his book
More example sentences
  • I mean, people singing along to songs, even horribly out of key, is better than groups of people talking loudly in some sort of strange choir.
  • Here, though, they're wavering, sliding in and out of key.
  • Every song is sure to be awesome and sung out of key.
See parent entry: key