bang1
  
  n.
   - a sudden loud, sharp noise. 
▸a sudden painful blow.
 - 
(bangs)
 N. Amer. a fringe of hair cut straight across the forehead.
 - Computing,  chiefly N. Amer. the character ‘!’.
 
v.
  - strike or put down forcefully and noisily. 
▸make or cause to make a sudden loud noise.
 - vulgar slang (of a man) have sex with.
 
adv.
 informal, chiefly Brit. exactly:
 the train arrived bang on time.
 
  Phrase
  
    - bang for one's 
(or the)
 buck
 N. Amer. informal value for money.  - bang goes something
 informal a plan or hope is suddenly or completely destroyed.  - bang on
 Brit. informal exactly right.  - get a bang out of
 N. Amer. informal derive excitement or pleasure from.  - with a bang
  - abruptly.
 - impressively.
 
 
   
  Phrase verbal
  
    - bang away at
 informal do persistently or doggedly.  - bang on about
 Brit. informal talk at tedious length about.  - bang something out
 informal  - play music noisily and unskilfully.
 - produce something hurriedly or in great quantities.
 
  - bang someone up
 Brit. informal imprison someone. 
   
  Etymology
  C16: imitative, perh. of Scand. origin.