A Necessity

1. The quality or state of being necessary, unavoidable, or absolutely requisite.
2. The condition of being needy; desperate need; lack.
3. Something necessary; a requisite; something indispensable.
4. Something which makes an act or an event unavoidable; an irresistible force; overruling power.
5. The negation of freedom in voluntary action; the subjection of all phenomena, whether material or spiritual, to inevitable causation; necessitarianism. (Can we add an example for this sense?)
6. (law) Greater utilitarian good; used in justification of a criminal act.

doctrine of necessity

7. (law, in the plural) Indispensable requirements (of life).

Synonyms

• (state of being necessary): inevitability, certainty

Antonyms

• (state of being necessary): impossibility, contingency
• (something indispensable): luxury