alert

Definitions

General English

  • adjective watching or listening carefully, ready to notice something

Aviation

  • adjective fully awake, watchful and ready to deal with any situation

Computing

Electronics

  • In computers, a visible and/or audible signal that serves to notify, remind, or warn. It can refer, for example, to an error, a calendar event, or to inform that a process is completed.

Military

  • adjective watchful and ready to take action
  • noun a warning of a threat or danger
  • verb to warn someone of a danger or change in situation, or to inform someone about an incident

Slang

  • adjective (of a male) slightly sexually aroused. Related terms, also in use since 2000, include lob-on and semi. ‘It means to be a bit turned on (i.e. having a slight erection)’. (Recorded, London student, May 2003).

Sports

  • adjective used for describing someone who takes an intelligent interest in his or her surroundings

Origin & History of “alert”

Alert comes, via French, from an Italian phrase all’ erta ‘on the look-out’, or literally ‘at the (alla) watch-tower (erta)’. Erta was short for torre erta, literally ‘high tower’, in which the adjective erta ‘high’ came ultimately from Latin ērectus, the past participle of ērigere ‘raise’.
http://www.dictionarycentral.com/definition/alert.html