Synonyms:
* Crisis: A time of great difficulty or danger.
* Urgency: The state of being urgent or requiring immediate attention.
* Catastrophe: A sudden event causing great and widespread damage or suffering.
* Hardship: A difficult or unfortunate situation.
* Dire straits: A very difficult or dangerous situation.
* Impasse: A situation in which no progress can be made.
* Dilemma: A situation in which a difficult choice has to be made.
* Conflagration: A large, destructive fire.
Antonyms:
* Routine: A normal or usual procedure or practice.
* Peace: A state of tranquility or freedom from disturbance.
* Calm: A state of being peaceful and untroubled.
* Tranquility: A state of peace and quiet.
* Stability: The state of being firm, steady, and not easily changed.
* Harmony: A state of peaceful coexistence or agreement.
* Security: The state of being free from danger or threat.
* Normalcy: The state of being normal or usual.
It's important to note that the best synonym or antonym will depend on the specific context in which the word "emergency" is used.