, not, and _evito_, shun) is primarily the exact
equivalent of the Saxon _unavoidable_; both words are applied to things
which some at least would escape or prevent, while that which is
_necessary_ may meet with no objection; food is _necessary_, death is
_inevitable_; a _necessary_ conclusion satisfies a thinker; an
_inevitable_ conclusion silences opposition. An _infallible_ proof is
one that necessarily leads the mind to a sound conclusion. _Needed_ and
_needful_ are more concrete than _necessary_, and respect an end to be
attained; we speak of a _necessary_ inference; _necessary_ food is what
one can not live without, while _needful_ food is that without which he
can not enjoy comfort, health, and strength.

Antonyms:

casual, needless, optional, useless,
contingent, non-essential, unnecessary, worthless.

Prepositions:

Necessary _to_ a sequence or a total; _for_ or _to_ a result or a
person; unity is necessary _to_ (to constitute) completeness; decision
is necessary _for_ command, or _for_ a commander.

* * * * *

NECESSITY.

Synonyms:

compulsion, fatality, requisite,
destiny, fate, sine qua non,
emergency, indispensability, unavoidableness,
essential, indispensableness, urgency,
exigency, need, want.
extremity, requirement,

_Necessity_ is the quality of being necessary, or the quality of that
which can not but be, become, or be true, or be accepted as true. _Need_
and _want_ always imply a lack; _necessity_ may be used in this sense,
but in the higher philosophical sense _necessity_ simply denotes the
exclusion of any alternative either in thought or fact; righteousness is
a _necessity_ (not a _need_) of the divine nature. _Need_ suggests the
possibility of supplying the deficiency which _want_ expresses; to speak
of a person's _want_ of decision merely points out a weakness in his
character; to say that he has _need_ of decision implies that he can
exercise or attain it. As applied to a deficiency, _necessity_ is more
imperative than _need_; a weary person is in _need_ of rest; when rest
becomes a _necessity_ he has no choice but to stop work. An _essential_
is something, as a quality, or element, that belongs to the essence of
something else so as to be inseparable from it in its normal condition,
or in any complete idea or statement of it. Compare NECESSARY;
PREDESTINATION.