assertion
US /əˈsɝː.ʃən/
UK /əˈsɝː.ʃən/

1.
a confident and forceful statement of fact or belief
:
•
His assertion that the company was failing proved to be false.
•
The politician made a bold assertion about economic growth.
2.
the action of asserting something
:
•
The lawyer's strong assertion of his client's innocence impressed the jury.
•
She defended her rights with a firm assertion of her beliefs.