master

an artist of consummate skill; "a master of the violin"; "one of the old masters"

a person who has general authority over others

a combatant who is able to defeat rivals

directs the work of others

presiding officer of a school

an original creation (i.e., an audio recording) from which copies can be made

an officer who is licensed to command a merchant ship

someone who holds a master's degree from academic institution

an authority qualified to teach apprentices

key that secures entrance everywhere

be or become completely proficient or skilled in; "She mastered Japanese in less than two years"

get on top of; deal with successfully; "He overcame his shyness"

have dominance or the power to defeat over; "Her pain completely mastered her"; "The methods can master the problems"

have a firm understanding or knowledge of; be on top of; "Do you control these data?"

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"