twayblade

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of numerous small terrestrial orchids of the genera Liparis and Listera, having usually two basal leaves and a terminal cluster of greenish or purplish flowers.

Century Dictionary and Cyclopedia

1. n. Primarily, a European orchid, Listera ovata, a simple-stemmed plant a foot or more high, bearing a slender raceme of green flowers, and about six inches from the ground a single pair of broadly ovate leaves, to which the name refers. The name is extended to the other species of the genus, 3 of which are found in North America, L. convallarioides being the most notable. In America the name is also applied to the members of the genus Liparis, which bear two leaves, springing, however, from the root L. liliifolia, with purple flowers, is a very handsome species.

Wiktionary

1. n. Any of several orchids, of the genera Lipara and Listera, that have a pair of basal leaves

GNU Webster's 1913

1. n. (Bot.) Any one of several orchidaceous plants which have only two leaves, as the species of Listera and of Liparis.

WordNet 3.0

1. n. orchid having a pair of ovate leaves and a long slender raceme of green flowers sometimes tinged red-brown; Europe to central Asia
2. n. an orchid of the genus Liparis having a pair of leaves