mistletoe

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A Eurasian parasitic shrub (Viscum album) having leathery evergreen leaves and waxy white berries.
2. n. Any of several American parasitic shrubs, such as Phoradendron flavescens of eastern North America.
3. n. A sprig of mistletoe, often used as a Christmas decoration.

Century Dictionary and Cyclopedia

1. n. A European plant, Viscum album, of the natural order Loranthaceæ, growing parasitically on various trees. It is a jointed dichotomous shrub, with sessile, oblong, entire leaves, and small yellowish-green flowers, the whole forming a pendent bush, which is covered in winter with small white berries containing a glutinous substance. The shrub is said to be disseminated by birds, which eat the berries and disperse the undigested seeds in their droppings. It is found on a great variety of trees, especially the apple-tree, but seldom on the oak. The mistletoe (compare def. 2) was consecrated to religious purposes by the ancient Celtic nations of Europe, and was held in peculiar veneration by the Druids, especially when found growing on the oak. Traces of this old superstitious regard for the mistletoe still survive in European countries, as in the custom of kissing under it at Christmas. It was formerly highly esteemed as an antispasmodic. but is not now so used. It seems, however, to have some pharmaco-dynamic properties.
2. n. A plant of some other species of Viscum, or of one of the genera Loranthus, Phoradendron, and Arceuthobium, their species almost all having the same parasitic habit. The mistletoe (Viscum) mentioned by Latin writers in their account of the Druids is thought by some to have been Loranthus Europœus of southern Europe, said to grow on a species of oak in the south of France. The mistletoe of the eastern United States is Phoradendron flavescens, common on various trees, especially the tupelo and red maple. See gad-bush.

Wiktionary

1. n. Any of several parasitic evergreen plants with white berries that grow in the crowns of oaks, apple trees and other trees.
2. n. A sprig of these plants used as a Christmas decoration.

GNU Webster's 1913

1. n. (Bot.) A parasitic evergreen plant of Europe (Viscum album), bearing a glutinous fruit. When found upon the oak, where it is rare, it was an object of superstitious regard among the Druids. A bird lime is prepared from its fruit.

WordNet 3.0

1. n. shrub of central and southeastern Europe; partially parasitic on beeches, chestnuts and oaks
2. n. American plants closely resembling Old World mistletoe
3. n. Old World parasitic shrub having branching greenish stems with leathery leaves and waxy white glutinous berries; the traditional mistletoe of Christmas