Definition of "emergency"

emergency

/ɪˈmɜː(ɹ).dʒən.si/

noun
plural emergencies
1. A situation which poses an immediate risk and which requires urgent attention.
2. The department of a hospital that treats emergencies.
  Quotations
  I've got a really bad diseaseIt's got me begging on my hands and kneesSo take me to emergencyCause something seems to be missing
  2009, “Restless Heart Syndrome”, in 21st Century Breakdown, performed by Green Day
3. An individual brought in at short notice to replace a member of staff, a player in a sporting team, etc.
  Quotations
  Van Gaal responded by replacing Adnan Januzaj with Carrick and, in fairness, the emergency centre-half did exceedingly well given that he has not played since May.
  November 2 2014, Daniel Taylor, "Sergio Agüero strike wins derby for Manchester City against 10-man United," guardian.co.uk
4. (attributive) Arising from or used in an emergency.
  Quotations
  We also found that the only emergency egress from the tram was by smashing the front or rear windscreens, and that emergency lighting had failed when the tram overturned.
  2021 December 29, Dominique Louis, “Causal analysis: crashworthiness at Sandilands”, in RAIL, number 947, page 33
5. (archaic) The quality of being emergent; sudden or unexpected appearance; an unforeseen occurrence.