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Webster 1913 Edition
Regnant
1.
Exercising regal authority; reigning;
as, a queen
. regnant
2.
Having the chief power; ruling; predominant; prevalent.
“A traitor to the vices regnant.” Swift.
Webster 1828 Edition
Regnant
REG'NANT
,Adj.
1.
Reigning; exercising regal authority; as a queen regnant. The modern phrase is queen regent.2.
Ruling; predominant; prevalent; having the chief power; as vices regnant. We now say, reigning vices.