Origin: OE. Necessite, F. Necessite, L. Necessitas, fr. Necesse. See Necessary.
3. That which is necessary; a necessary; a requisite; something indispensable; often in the plural. These should be hours for necessities, Not for delights. (Shak) What was once to me Mere matter of the fancy, now has grown The vast necessity of heart and life. (Tennyson)
4. That which makes an act or an event unavoidable; irresistible force; overruling power; compulsion, physical or moral; fate; fatality. So spake the fiend, and with necessity, The tyrant's plea, excused his devilish deeds. (milton)
5. (Science: psychology) The negation of freedom in voluntary action; the subjection of all phenomena, whether material or spiritual, to inevitable causation; necessitarianism. Of necessity, by necessary consequence; by compulsion, or irresistible power; perforce.
Synonym: See need.