Definition of necessary

< necessarily

necessitarianism >

nec·es·sar·y    (ns-sr) KEY 

ADJECTIVE:

1. Absolutely essential. See Synonyms at indispensable.
2. Needed to achieve a certain result or effect; requisite: the necessary tools.
3. 1. Unavoidably determined by prior conditions or circumstances; inevitable: the necessary results of overindulgence.
   2. Logically inevitable.
4. Required by obligation, compulsion, or convention: made the necessary apologies.

NOUN:
pl. nec·es·sar·ies

Something indispensable.

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ETYMOLOGY:
Middle English necessarie, from Old French necessaire, from Latin necessrius, from necesse; see ked- in Indo-European roots