off-key
🇺🇸
/ˌɔːf ˈkiː/
🇬🇧
/ˌɒf ˈkiː/
Sounding not quite right, as if the pitch is incorrect.
When the choir sang the song, one voice was off-key, making everything sound weird.
Not appropriate or fitting for a particular situation.
His joke was off-key during the serious meeting, making it awkward.