ˌred aˈlert BrE AmE noun [countable usually singular, uncountable]
a warning that there is very great danger
be (put/placed) on red alert
All the hospitals are on red alert.
ˌred aˈlert BrE AmE noun [countable usually singular, uncountable]
a warning that there is very great danger
be (put/placed) on red alert
All the hospitals are on red alert.
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012