Common words that rhyme with assertion include insertion, portion, affection, adoration, infatuation, inclination, appreciation, nation, condemnation, vacation, sanction, confirmation, preparation, expectation and exception.
He ate a large portion of the cake.
She showed her affection for him.
She practiced the ritual with great devotion.
Her cheerful disposition brightens the room.
I showed my appreciation for kindness.
The nation is in political turmoil.