to be / not be singing or playing the correct musical notes to sound pleasant :
None of them could sing in tune.
The piano is out of tune.
to be / not be singing or playing the correct musical notes to sound pleasant :
None of them could sing in tune.
The piano is out of tune.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005