Learner's definition of NOTION
1 [count] : an idea or opinion
He has some pretty strange notions.
I only have a (slight) notion of the poem's meaning.
She had a vague notion about what happened.
They have different notions [=conceptions] of right and wrong.
The study disproves any notion that dolphins are not intelligent.
2 [count] : an idea about doing something : a sudden wish or desire 3 notions [plural], US : small useful things (such as pins, thread, and buttons) that are used for sewing