buck in WordNet English dictionary

1. mature male of various mammals (especially deer or antelope)
   buck 
   
2. a framework for holding wood that is being sawed
   sawhorse  horse  sawbuck  buck 
   
3. a gymnastic horse without pommels and with one end elongated; used lengthwise for vaulting
   vaulting horse  long horse  buck 
   
4. a piece of paper money worth one dollar
   dollar  dollar bill  one dollar bill  buck  clam 
   

1. jump vertically, with legs stiff and back arched
   "the yung filly bucked"
   buck  jerk  hitch 
   
2. move quickly and violently
   "The car tore down the street"; "He came charging into my office"
   tear  shoot  shoot down  charge  buck 
   
3. resist
   "buck the trend"
   buck  go against 
   
4. to strive with determination
   "John is bucking for a promotion"
   buck