do something on sight
As soon as someone or something is or can be seen. Police have orders to shoot the suspect on sight.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
do something on ˈsightdo or feel something as soon as you see somebody/something: She complained constantly about the hotel, which she hated on sight. ♢ The soldiers were ordered to shoot on sight.
Farlex Partner Idioms Dictionary © Farlex 2017