(1):

An invention; an ingenious device; a knickknack; as, Yankee notions.

(2):

Inclination; intention; disposition; as, I have a notion to do it.

(3):

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 notae.

(4):

Sense; mind.

(5):

A sentiment; an opinion.