notion
noun
°Mental apprehension of whatever may be known or imagined; an idea; a conception; more properly, a general or universal conception, as distinguishable or definable by marks or notæ.
"What hath been generally agreed on, I content myself to assume under the notion of principles. - Sir Isaac Newton."
°A sentiment; an opinion.
"The extravagant notion they entertain of themselves. - Joseph Addison."