The Collaborative International Dictionary of English v.0.48:

Necessity \Ne*ces"si*ty\, n.; pl. Necessities. [OE. necessite,
   F. n['e]cessit['e], L. necessitas, fr. necesse. See
   Necessary.]
   1. The quality or state of being necessary, unavoidable, or
      absolutely requisite; inevitableness; indispensableness.
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   2. The condition of being needy or necessitous; pressing
      need; indigence; want.
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            Urge the necessity and state of times. --Shak.
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            The extreme poverty and necessity his majesty was
            in.                                   --Clarendon.
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   3. That which is necessary; a necessary; a requisite;
      something indispensable; -- often in the plural.
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            These should be hours for necessities,
            Not for delights.                     --Shak.
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            What was once to me
            Mere matter of the fancy, now has grown
            The vast necessity of heart and life. --Tennyson.
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   4. That which makes an act or an event unavoidable;
      irresistible force; overruling power; compulsion, physical
      or moral; fate; fatality.
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            So spake the fiend, and with necessity,
            The tyrant's plea, excused his devilish deeds.
                                                  --Milton.
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   5. (Metaph.) The negation of freedom in voluntary action; the
      subjection of all phenomena, whether material or
      spiritual, to inevitable causation; necessitarianism.
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   Of necessity, by necessary consequence; by compulsion, or
      irresistible power; perforce.
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   Syn: See Need.
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