regnant

1. not comparableReigning, ruling; currently holding power.First known use 15th c.

   The people are now the State, their will is the regnant will, and that will has this characteristic — it loves principles, it hates compromises; and the principles it loves must be regulative, fit to be applied to the work and guidance of life.

   1910, A. M. Fairbairn, Studies in Religion and Theology, page 99

2. not comparableDominant; holding sway; having particular power or influence.First known use 17th c.

   The doors of his temples were kept open in time of war, the time in which the ideas of contradiction and conflict are most naturally regnant.

   2010, Christopher Hitchens, Hitch-22, Atlantic, published 2011, page 7

3. not comparablepostpositionalof a monarch, ruling in one's own right; often contrasted with consort and dowager

   Queen Elizabeth II reigned as queen regnant, unlike her mother Queen Elizabeth The Queen Mother.

plural regnants

1. obsoleteA sovereign or ruler.

   Here are two sovereigns in the land, a regnant and a claimant—that is enough of one good thing—but if any one wants more, he may find a king in every peel-house in the country; so if we lack government, it is not for lack of governors—[…]

   1820, [Walter Scott], chapter XI, in The Abbot. […], volume II, Edinburgh: […] [James Ballantyne & Co.] for Longman, Hurst, Rees, Orme, and Brown, […]; and for Archibald Constable and Company, and John Ballantyne, […], →OCLC, page 339