The American Heritage® Dictionary of the English Language, 4th Edition
n. A Eurasian mint (Mentha pulegium) having small lilac-blue flowers and ovate or nearly orbicular leaves that yield a useful, aromatic oil.
n. An aromatic plant (Hedeoma pulegioides) of eastern North America, having purple-blue flowers and glabrous leaves that yield an oil used as an insect repellent.
n. A plant of the mint family, Mentha pulegium, formerly much used in various medicinal treatments and as a flea repellant.
the GNU version of the Collaborative International Dictionary of English
n. An aromatic herb (Mentha Pulegium) of Europe; also, a North American plant (Hedeoma pulegioides) resembling it in flavor.
The Century Dictionary and Cyclopedia
n. A much-branched prostrate perennial herb, Mentha Pulegium, of Europe and western Asia.
n. A plant of the genus Hedeoma; the American pennyroyal. See Hedeoma, and oil of hedeoma (under oil).
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. erect hairy branching American herb having purple-blue flowers; yields an essential oil used as an insect repellent and sometimes in folk medicine
n. Eurasian perennial mint have small lilac-blue flowers and ovate leaves; yields an aromatic oil
Word Usage
"The herb we call pennyroyal was the only one I found in abundance, and that only on the brows, where the ground had been partially cleared; vegetation is impossible elsewhere, and it is this circumstance which makes the “eternal forests” of"