Pennyroyal
Pennyroyal , noun
[A corruption of Old English puliall royal. Old English puliall is ultimately derived from Latin puleium, or pulegium regium (so called as being good against fleas), from pulex a flea; and royal is a translation of Latin regium, in puleium regium.]
(Botany) An aromatic herb (Mentha Pulegium) of Europe; also, a North American plant (Hedeoma pulegioides) resembling it in flavor.