v.
 (past and past part. fought)
   - take part in a violent struggle involving physical force or weapons. 
▸engage in (a war or contest).
 ▸quarrel or argue.
 ▸
(fight someone/thing off)
 defend oneself against an attack by someone or something.
 - struggle to overcome, eliminate, or prevent. 
▸try very hard to obtain or achieve something:
 I will fight for a fairer society.
 - 
(fight one's way)
 move forward with difficulty.
 
n.
 an act of fighting. 
▸a vigorous struggle or campaign.
 ▸the inclination or ability to fight or struggle.
 
  Phrase
  
    - fight fire with fire
 use the weapons or tactics of one's opponent, even if one finds them distasteful.  - fight shy of
 be unwilling to undertake or become involved with.  - fight or flight
 the instinctive physiological response to a threatening situation, which readies one either to resist forcibly or to run away. 
   
  Etymology
  OE feohtan (v.), feoht(e), gefeoht (n.), of W. Gmc origin.