noun

• The quality or state of being necessary, unavoidable, or absolutely requisite.
• The condition of being needy; desperate need; lack.
• Something necessary; a requisite; something indispensable.
• Something which makes an act or an event unavoidable; an irresistible force; overruling power.
• The negation of freedom in voluntary action; the subjection of all phenomena, whether material or spiritual, to inevitable causation; necessitarianism.
• (law) Greater utilitarian good; used in justification of a criminal act.
• (law, in the plural) Indispensable requirements (of life).