• quick to notice any unusual and potentially dangerous or difficult circumstances; vigilant

Synonyms: vigilant, hypervigilant, wide awake, aware, watchful, attentive, observant, circumspect, wary, chary, heedful, canny

• the state of being watchful for possible danger

Synonyms: vigilance, watchfulness, carefulness, attentiveness, guardedness, care, caution, cautiousness, wariness, chariness, alertness, hypervigilance, circumspection, prudence, heedfulness, heed, mindfulness

• an announcement or signal warning of danger

Synonyms: warning, caution, notification, notice, exhortation, injunction

• warn (someone) of a danger or problem

Synonyms: warn, notify, apprise, caution, put on one's guard, forewarn, put on the qui vive, arouse