emergency

noun5

1. •
   [before a noun] a sudden dangerous situation that needs help or action right away

   • Cardiac arrest is an emergency requiring medical attention.
2. •
   (euphemistic) A critical urge to urinate or defecate.
3. •
   The department of a hospital that treats emergencies.

   • I've got a really bad disease It's got me begging on my hands and knees So take me to emergency Cause something seems to be missing — 2009
4. •
   A person brought in at short notice to replace a member of staff, a player in a sporting team, etc.

   • November 2 2014, Daniel Taylor, "Sergio Agüero strike wins derby for Manchester City against 10-man United," guardian.co.uk 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.
5. •
   (no longer used) The quality of being emergent; sudden or unexpected appearance; an unforeseen occurrence.