on the lookout

Idioms  

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).

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Example Sentences

Jarvis and Sir Keir are also on the lookout for a new armed forces minister, after the bizarre resignation of Al Carns.

From BBC • Jun. 12, 2026

Be on the lookout for a giant shovel.

From Los Angeles Times • Apr. 10, 2026

He was “worried about retirement and on the lookout for a final score,” Mr. Keefe writes.

From The Wall Street Journal • Apr. 10, 2026

They will also be on the lookout for possible flashes of light caused by meteorites crashing into the surface of the Moon.

From Barron's • Apr. 5, 2026

And he must be scared to make any noise, because now Erik’s on the lookout for a rat.

From "Invisible Inkling" by Emily Jenkins

Related Words

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