Assert (verb)

1. To state a fact or belief confidently and forcefully.
2. To take a firm stand for something.

Origin:

From the latin word "assertus" meaning "affirm" or "assert oneself".

Examples:

1. He asserted that he was innocent.
2. She asserted her authority in the situation.
3. The company asserted its rights in the matter.
4. He asserted his dominance in the game.
5. The lawyer asserted his client's innocence.