an eagle eye
1. Excellent eyesight, especially for something in particular. I have an eagle eye for spotting wildlife.
2. An ability to discern small details; a keen skill of observation. We need to get Sally's eagle eye on this manuscript because she'll be sure to spot any errors.
3. An attentive gaze. You need to keep an eagle eye on the kids because they will get into everything the minute you turn your back.
4. One who is apt to discern small details or pay close attention to someone or something. Ugh, I got a demerit because some eagle eye saw me with my shirt untucked during yesterday's assembly.
an eagle eye
If someone has an eagle eye, they watch things carefully and are good at noticing things. No antiques shop, market or furniture shop escapes her eagle eye. Phil's played first-class cricket for five years in England under the eagle eye of our umpires. You must watch builders with an eagle eye because some will cheat the minute you turn your back. Note: You can also say that someone keeps an eagle eye on someone or something. Managers of Europe's top clubs are keeping an eagle eye on the World Championships, hoping to snap up new talent. Note: You can also describe someone as eagle-eyed. As the band were passing through security, an eagle-eyed official spotted an 18-inch knife in their luggage. Note: Eagles have very good eyesight, and are able to see small animals or objects from a great height.