vigilant

Definitions

Keeping careful watch for possible danger or difficulties.

Alertly watchful, especially to avoid danger.

Examples

The security guard remained vigilant throughout the night to ensure the safety of the building.

Parents must be vigilant when their children are playing near busy roads.

Synonyms

alert watchful attentive observant wary cautious sharp

Antonyms

negligent inattentive careless unobservant heedless distracted lax