notion (nom)
Sens 1 : a mental apprehension or picture of whatever may be known or imagined:
the meaning or content assigned by the mind to a term: conception, idea. [source : MWU]
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Sens 2 : a general or universal concept. [source : MWU]
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Sens 3 : a complex idea that has its original and constant existence in the
thoughts of men rather than in the reality of things. [source : MWU]
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Sens 4 : an idea, theory, or belief held by someone. [source : MWU]