master in WordNet English dictionary

1. an officer who is licensed to command a merchant ship
   master  captain  sea captain  skipper 
   
2. presiding officer of a school
   headmaster  schoolmaster  master 
   
3. a person who has general authority over others
   overlord  master  lord 
   
4. an artist of consummate skill
   "a master of the violin"; "one of the old masters"
   maestro  master 
   
5. an original creation (i.e., an audio recording) from which copies can be made
   master  master copy  original 
   
6. key that secures entrance everywhere
   passkey  passe-partout  master key  master 
   
7. a combatant who is able to defeat rivals
   victor  master  superior 
   
8. an authority qualified to teach apprentices
   master  professional 
   
9. directs the work of others
   master 
   
10. someone who holds a master's degree from academic institution
    master 
    

1. most important element
   "the chief aim of living"; "the main doors were of solid glass"; "the principal rivers of America"; "the principal example"; "policemen were primary targets"; "the master bedroom"; "a master switch"
   chief  main  primary  principal  master 
   

1. have a firm understanding or knowledge of; be on top of
   "Do you control these data?"
   master  control 
   
2. have dominance or the power to defeat over
   "Her pain completely mastered her"; "The methods can master the problems"
   dominate  master 
   
3. get on top of; deal with successfully
   "He overcame his shyness"
   overcome  get over  subdue  surmount  master 
   
4. be or become completely proficient or skilled in
   "She mastered Japanese in less than two years"
   master  get the hang