Webster's Revised Unabridged Dictionary · 1913

Regnant

Regnant (-nant) , adjective

[Latin regnans, -antis, present participle of regnare to reign: compare F régnant. See Reign.]

1.
Exercising regal authority; reigning; as, a queen regnant.
2.
Having the chief power; ruling; predominant; prevalent.
A traitor to the vices regnant. — Swift