on guard


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on (one's) guard

Especially careful or vigilant; prepared for danger or surprises. He's got a lot of tricky moves, so be on your guard! Those trails can be a bit treacherous to climb. I just hope she's on her guard.
See also: guard, on
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

*on (one's) guard (against someone or something)

alert against someone or something. (*Typically: be ~; keep ~; remain ~; stay ~.) Try to stay on guard against pickpockets. I am always on my guard. Be on guard when you go into the city.
See also: guard, on
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.

on (one's) guard

Alert and watchful; cautious.
See also: guard, on
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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