because of the possibility of sth happening, although it is unlikely :
I didn't think you'd be at home but I just called by on the off chance.
because of the possibility of sth happening, although it is unlikely :
I didn't think you'd be at home but I just called by on the off chance.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005