{n. phr.} A slight glance; a quick look. * /The substitute teacher could see with half an eye that she was going to have trouble with the class./ * /While Mary was cooking she kept half an eye on the baby to see that he didn't get into mischief./
HALF AN EYE
Meaning of HALF AN EYE in English
Dictionary of English idioms . Словарь английских идиом. 2012