Definition of mightiness :
1. Highness; excellency; - with a possessive pronoun, a title of dignity; as, their high mightinesses.
2. The quality of being mighty; possession of might; power; greatness; high dignity.
authority (part of speech: noun)
influence, title, commission, precedence, control, privilege, might, potency, purview, power, strength, credential, punch, superiority, sway, enfranchisement, stature, clout, puissance, charge, kingship, license, steam, seniority, prestige, mastery, powerfulness, prepotency, prerogative, command, authority, right, empowerment, mandate, domination, birthright, primacy, entitlement, rank, sovereignty, faculty, office, force, cogency
- History describes, and is meant to describe, forces, not proprieties- the mights, the acted realities of men, bad and good- their historical importance depending on their mightiness, not their holiness. - "Thomas Davis, Selections from his Prose and Poetry", Thomas Davis Commentator: T. W. Rolleston.
- The mondes thought it terribly wicked, not the deed you know, but the audacity of a cavalry man's having potted a Very Serene High Mightiness. - "Cecil Castlemaine's Gage, Lady Marabout's Troubles, and Other Stories", Ouida.
- You want woman to be a mere lump of sugar, content to be left in a bowl until it pleases you in your high- and- mightiness to take her in the tongs and drop her into the coffee of your existence, to sweeten what would otherwise not please your taste- and like most men you prefer two or three lumps to one. - "The Enchanted Typewriter", John Kendrick Bangs.