What is the meaning of Notion?

Mental apprehension of whatever may be known, thought, or imagined; idea, concept.

A sentiment; an opinion.

Sense; mind.

An invention; an ingenious device; a knickknack.

Any small article used in sewing and haberdashery, either for attachment to garments or as a tool, such as a button, zipper, or thimble.

Inclination; intention; predisposition; disposition.

Pretentiousness or overambition.

notion

an elementary treatise

Source: wiktionary.org