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definitions

red alert

noun
  1. (in military or civilian defense) the most urgent form of alert, signaling that an enemy attack is believed to be imminent.
  2. the signal or alarm sounded for this alert.Compare blue alert, white alert, yellow alert.
  3. a signal or warning that a critical situation is developing or has occurred.
  4. the period during which a state of crisis or danger is declared to exist.

Origin of red alert

First recorded in 1960–65
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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