on the lookout

1. 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).

Example Sentences

As summer heats up and tourists flock to the California coast, beachgoers should be on the lookout for sea lions sickened by a recent outbreak of leptospirosis — a kidney disease that can result in severe symptoms in both humans and animals.

From Los Angeles Times

The head coach is on the lookout for at least three more new faces in offensive areas.

From BBC

“I think it’s something that we will be on the lookout for,” she said.

From Los Angeles Times

Music lovers on the lookout for the fabled “Electric Nebraska” LP will be sorely disappointed.

From Salon

Beijing has ramped up warnings of foreign spies, telling civilians to be on the lookout for suspicious figures.

From BBC

Related Words

• active 
• bright 
• careful 
• intelligent 
• observant 
• perceptive 
• sharp 
• vigilant 
• wary 
• watchful 
• wired 
• wise