king in WordNet English dictionary

1. a very wealthy or powerful businessman
   "an oil baron"
   baron  big businessman  business leader  king  magnate  mogul  power  top executive  tycoon 
   
2. (chess) the weakest but the most important piece
   king 
   
3. one of the four playing cards in a deck bearing the picture of a king
   king 
   
4. a checker that has been moved to the opponent's first row where it is promoted to a piece that is free to move either forward or backward
   king 
   
5. a male sovereign; ruler of a kingdom
   king  male monarch  Rex 
   
6. a competitor who holds a preeminent position
   king  queen  world-beater 
   
7. preeminence in a particular category or group or field
   "the lion is the king of beasts"
   king