notion

(noun) a vague idea in which some confidence is placed. Synonyms: impression, feeling, belief, opinion. Examples: "His impression of her was favorable." "What are your feelings about the crisis?." "It strengthened my belief in his sincerity." "I had a feeling that she was lying."

(noun) a general inclusive concept.

(noun) an odd or fanciful or capricious idea. Synonyms: whim, whimsy, whimsey. Examples: "The theatrical notion of disguise is associated with disaster in his stories." "He had a whimsy about flying to the moon." "Whimsy can be humorous to someone with time to enjoy it."

(noun) (usually plural) small personal articles or clothing or sewing items. Example: "Buttons and needles are notions."