名詞 necessity:

1. the condition of being essential or indispensable
2. anything indispensable
   同義詞：essential, requirement, requisite, necessary

1. It was done under the pressure of the necessity.
   這件事是在迫切需要的情況下而做的。
2. Necessity is the mother of invention.
   需要是發(fā)明之母。
3. The doctor asked us to call him during the night except in case of necessity.
   醫(yī)生吩咐我們，除非必須，否則不要在夜里叫他。

ne.ces.si.ty

n.（名詞）
【復數(shù)】 ne.ces.si.ties

The condition or quality of being necessary.
需要：需要的條件或性質(zhì)
Something necessary:
必需品：必需的東西：
例句：
The necessities of life include food, clothing, and shelter.
生命的必需的，包括食物，衣服，住處

Something dictated by invariable physical laws.
必然性：由不變的自然規(guī)律決定的東西
The force exerted by circumstance.
必然力：環(huán)境施加的壓力
The state or fact of being in need.
需要：需要的狀態(tài)或事實
Pressing or urgent need, especially that arising from poverty.See Synonyms at need
困難，危急：急切的，緊迫的需要，尤其是從貧窮中產(chǎn)生的參見 need

<習慣用語>of necessity
As an inevitable consequence; necessarily.
無法避免的；必然地
來源：
Middle English necessite
中古英語 necessite
from Old French
源自 古法語
from Latin necessit3s
源自 拉丁語 necessit3s
from necesse [necessary] * see necessary
源自 necesse [必然的] *參見 necessary