sumac

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various shrubs or small trees of the genus Rhus, having compound leaves, clusters of small greenish flowers, and usually red, hairy fruit. Some species, such as the poison ivy and poison oak, cause an acute itching rash on contact.

Century Dictionary and Cyclopedia

1. n. One of numerous shrubs or small trees of the genus Rhus. See def. 2, and phrases below.
2. n. A product of the dried and ground leaves of certain shrubs or trees of the genus Rhus or of other genera, much used for tanning light-colored leathers and to some extent for dyeing. The leading source of this product is the tanners' or Sicilian sumac, Rhus Coriaria, of southern Europe, cultivated in Sicily and also in Tuscany. The Venetian sumac, smoke-tree, or wig-tree, R. Cotinus, is grown in Tyrol for the same purpose. (See smoke-tree and scotino.) In Spain various species supply a similar substance, and in Algeria the leaves of R. pentaphylla, five-leaved or Tezera sumac, are applied to the manufacture of morocco. In France a tree of another genus, Coriaria myrtifolia, myrtle-leaved sumac, furnishes a similar product. (See Coriaria.) In the United States, particularly in Virginia, the leaves of several wild sumacs are now gathered as tan-stock—namely, of the dwarf, the smooth, the stag-horn, and perhaps the Canadian sumac. These contain more tannin than the European, but, at least with careless gathering, they make an inferior leather.
3. In leather manufacturing, to treat with sumac.

Wiktionary

1. n. Any of various shrubs or small trees of the genus Rhus including the poison ivy and poison oak.
2. n. A sour spice popular in the Eastern Mediterranean made from the berries of the plant.

GNU Webster's 1913

1. n. (Bot.) Any plant of the genus Rhus, shrubs or small trees with usually compound leaves and clusters of small flowers. Some of the species are used in tanning, some in dyeing, and some in medicine. One, the Japanese Rhus vernicifera, yields the celebrated Japan varnish, or lacquer.
2. n. The powdered leaves, peduncles, and young branches of certain species of the sumac plant, used in tanning and dyeing.

WordNet 3.0

1. n. wood of a sumac
2. n. a shrub or tree of the genus Rhus (usually limited to the non-poisonous members of the genus)