mastery LIME quaternary BFFF00;191,255,0 masterynounmas·tery | \ ˈma-st(ə-)rē \Definition of mastery1a: the authority of a master : DOMINIONb: the upper hand in a contest or competition : SUPERIORITY, ASCENDANCY2a: possession or display of great skill or techniqueb: skill or knowledge that makes one master of a subject: COMMAND Each color has a corresponding gemstone that is correlative to its philosophical meaning and metaphysical purpose.