on the lookout

on the lookout (for someone or something)

watchful for someone or something. Be on the lookout for signs of a storm. I'm on the lookout for John, who is due here any minute.
See also: lookout, on

on the lookout

Also, on the watch. Vigilant, alert, as in Be on the lookout for the twins-they're somewhere on this playground, or He was on the watch for her arrival. Both phrases were originally used with upon. Upon the lookout was originally nautical usage, meaning "on duty being watchful" (as for another ship, rocks, or land); it appeared in the mid-1700s, and on replaced upon about a century later. Upon the watch was first recorded in Daniel Defoe's Robinson Crusoe (1719), and on the watch in Jane Austen's Sense and Sensibility (1797).
See also: lookout, on
References in classic literature ?
I, too, am well now: one of my eyes was sore but now I am on the lookout with both.
And what does he mean by 'One of my eyes was sore but now I am on the lookout with both'?
Istinctively, unconsciously, with every book, with every conversation, with every man he met, he was on the lookout for light on these questions and their solution.
My own hand placed it in one of the rouleaux of false half-crowns; and my own hand also directed the spurious coin, when it had been safely packed up, to a certain London dealer who was to be on the lookout for it by the next night's mail.
In the second place, the doctor would, in all probability, have occasion to write to his daughter, or would be likely to receive letters from her; and, if I quieted all suspicion on my account, by docile behavior, and kept my eyes sharply on the lookout, I might find opportunities of surprising the secrets of his writing-desk.
Nell is on the lookout for ten families from across the country to take part in a competition to lower their power bills.