Webster’s Revised Unabridged Dictionary · 1913
Assertion
As·ser′tion, n. [L. assertio, fr. asserere.] 1. The act of asserting, or that which is asserted; positive declaration or averment; affirmation; statement asserted; position advanced.
There is a difference between assertion and demonstration. Macaulay.
2. Maintenance; vindication; as, the assertion of one's rights or prerogatives.