be on guard

Meanings

1. 1phrasefixed phrase

   to be ready to deal with danger or trouble, and to watch carefully

   Grammar: Used after 'be' or other linking verbs: stay on guard, remain on guard. Often followed by 'against'.

   Patterns

   • be on guard
   • be on guard against something
   • stay on guard

   The soldiers were on guard all night at the entrance.

   Be on guard against pickpockets in crowded markets.

   She stayed on guard during the negotiation, ready to spot any lie.

2. 2phrasefixed phrasefigurative

   to be careful and not easily tricked or surprised

   Grammar: Often used in the continuous form: keeping someone on guard.

   Patterns

   • be on guard against something
   • keep someone on guard

   After the scandal, the company was on guard against further criticism.

   You should be on guard when someone offers you a deal that seems too good.

Common combinations

be on guard against

Travelers should be on guard against fake taxis.

stay on guard

Even after the storm passed, they stayed on guard.

put someone on guard

His strange questions put me on guard.

be on guard duty

Two officers were on guard duty at the gate.

Synonyms and how they differ

be alert

This means being quick to notice things; 'be on guard' adds the idea of expecting danger or trouble.

be vigilant

More formal and often used in official advice; 'be on guard' is more everyday.

watch out

This is more like a warning shout; 'be on guard' describes a continuing state of readiness.

Opposites

Word family

guard noun

a person who protects a place or person.

guard verb

to protect or watch over something.

Commonly confused: be on guard or on the guard?

Practice

Make it your own

Write a sentence using “be on guard”, then check it and compare it with the examples above.

Explore more words