Definition of "Master" :
noun: an original creation (i.e., an audio recording) from which copies can be made
noun: key that secures entrance everywhere
noun: presiding officer of a school
noun: an artist of consummate skill
"A master of the violin."
noun: an authority qualified to teach apprentices
noun: directs the work of others
noun: someone who holds a master's degree from academic institution
noun: an officer who is licensed to command a merchant ship
noun: a person who has general authority over others
noun: a combatant who is able to defeat rivals
verb: have a firm understanding or knowledge of; be on top of
verb: be or become completely proficient or skilled in
"She mastered Japanese in less than two years."
verb: get on top of; deal with successfully
verb: have dominance or the power to defeat over
"Her pain completely mastered her."
adjective: most important element
"The master bedroom."