to see sth by accident or not very clearly because you see it from the side of your eye and are not looking straight at it :
Out of the corner of her eye, she saw him coming closer.
to see sth by accident or not very clearly because you see it from the side of your eye and are not looking straight at it :
Out of the corner of her eye, she saw him coming closer.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005