as soon as someone or something is seen.

The law now requires all pigeons in the area to be shot on sight.

Even very young children can recognize certain words on sight.

• put your heads together
• put your heart and soul into
• put your heart and soul into doing something
• put your heart and soul into something
• put your heart into
• put your heart into something
• put your house in order
• put your life in hands
• put your life in someone's hands
• put your life on the line
• put your mind to it
• put your money on someone
• put your money on something
• put your money where mouth is
• put your money where your mouth is
• put your neck on the block
• put your neck on the line
• put your oar in
• put your own house in order
• put yourself in place
• put yourself in someone's place
• put yourself through
• put yourself through something
• put your shirt on
• put your shirt on something