on one's guard

Idioms  

1. see under off guard.

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Example Sentences

“Nature here is so strong that one has to be on one’s guard to not be absorbed by it,” wrote Dodge.

From Los Angeles Times

An Amusing Meeting in Orsera—Journey to Corfu—My Stay in Constantinople—Bonneval—My Return to Corfu—Madame F.—The False Prince—I Run Away from Corfu—My Frolics at Casopo—I Surrender My self a Prisoner—My Speedy Release and Triumph— My Success with Madame F. I affirm that a stupid servant is more dangerous than a bad one, and a much greater plague, for one can be on one's guard against a wicked person, but never against a fool.

From Project Gutenberg

To be on one's guard; to be cautious; to take care; Ð commonly followed by of or lest before the thing that is to be avoided.

From Project Gutenberg

Watchful; vigilant or on one's guard against danger or difficulty.

From Project Gutenberg

It is necessary also to be on one's guard against hasty assignments.

From Project Gutenberg