1. (n.) The quality of being needed, unavoidable, or absolutely requisite; inevitableness; indispensableness.

2. (n.) The condition of being needy or necessitous; pressing need; indigence; want.

3. (n.) That which is necessary; a necessary; a requisite; something indispensable; -- often in the plural.

4. (n.) That which makes an act or an event unavoidable; irresistible force; overruling power; compulsion, physical or moral; fate; fatality.

5. (n.) The negation of freedom in voluntary action; the subjection of all phenomena, whether material or spiritual, to inevitable causation.