fortitude CHARTREUSE tertiary 7FFF00,127,255,0 fortitudenounfor·ti·tude | \ ˈfȯr-tə-ˌtüd , –ˌtyüd \Definition of fortitude1: strength of mind that enables a person to encounter danger or bear pain or adversity with courage Each color has a corresponding gemstone that is correlative to its philosophical meaning and metaphysical purpose.