alert

1 alert /əˈlɚt/ adjective
1 alert
/əˈlɚt/
adjective
Britannica Dictionary definition of ALERT
[more alert; most alert]
: able to think clearly and to notice things
— often + to

— alertly

adverb

— alertness

noun [noncount]
2 alert /əˈlɚt/ noun
plural alerts
2 alert
/əˈlɚt/
noun
plural alerts
Britannica Dictionary definition of ALERT
1 
[count] : something (such as a message or loud sound) that tells people there is some danger or problem : an alarm or signal of danger
2 
[noncount] : the state of being ready for something you have been warned about (such as an attack) — used with on
— see also red alert

on the alert

: looking for or expecting something (such as danger or an opportunity) — often + for
3 alert /əˈlɚt/ verb
alerts; alerted; alerting
3 alert
/əˈlɚt/
verb
alerts; alerted; alerting
Britannica Dictionary definition of ALERT
[+ object]
1 
: to give (someone) important information about a possible problem, danger, etc. : to warn (someone)
2 
: to make (someone) aware of something
— often + to