v.
  - state a fact or belief confidently and forcefully.
- cause others to recognize (one's authority or a right) by confident and forceful behaviour. ▸
(assert oneself)
 behave or speak confidently and forcefully. 
Derivative
  
    
      - asserter 
(also assertor)
 n.
 
  Etymology
  C17 (earlier (ME) as assertion): from L. asserere ‘claim, affirm’, from ad- ‘to’ + serere ‘to join’.