Pennyroyal \Pen`ny*roy"al\, n. [A corruption of OE. puliall royal. OE. puliall is ultimately derived fr. L. puleium, or pulegium regium (so called as being good against fleas), fr. pulex a flea; and royal is a translation of L. regium, in puleium regium.]

(Bot.) An aromatic herb (Mentha Pulegium) of Europe; also, a North American plant (Hedeoma pulegioides) resembling it in flavor.

Bastard pennyroyal (Bot.) See Blue curls, under Blue.

Source: Webster's Revised Unabridged Dictionary (1913)