might·i·ness \ˈmīd.]ēnə̇s, -īt], ]in-\noun (-es) Etymology: Middle English mihtinesse, from mihty, mighty + -nesse -ness 1.: the quality or state of being mighty : possession of might : power 2.: highness, excellency — used as a title of dignity < Your Mightiness > < their High Mightinesses >