i Register
In some senses, alert is marked as obsolete. Watch for register when choosing this word.
adj
Attentive; awake; on guard.
brisk; nimble; moving with celerity.
I saw an alert young fellow that cocked his hat upon a friend of his who entered just at the same time with myself
noun
An alarm.
A notification of higher importance than an advisory.
A state of readiness for potential combat.
an airborne alert; ground alert
Synonym of bell (“bell character”).
verb
To give warning to.