acacia

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various often spiny trees or shrubs of the genus Acacia in the pea family, having alternate, bipinnately compound leaves or leaves represented by flattened leafstalks and heads or spikes of small flowers.
2. n. Any of several other leguminous plants, such as the rose acacia.
3. n. See gum arabic.

Century Dictionary and Cyclopedia

1. n. A genus of shrubby or arboreous plants, natural order Leguminosæ, suborder Mimoseæ, natives of the warm regions of both hemispheres, especially of Australia and Africa. It numbers about 430 species, and is the largest genus of the order, excepting Astragalus. It is distinguished by small regular flowers in globose heads or cylindrical spikes, and very numerous free stamens. The leaves are bipinnate, or in very many of the Australian species are reduced to phyllodia, with their edges always vertical. Several species are valuable for the gum which they exude. The bark and pods are frequently used in tanning, and the aqueous extract of the wood of some Indian species forms the catechu of commerce. Many species furnish excellent timber, and many others are cultivated for ornament —A. Farnesiana both for ornament and for the perfume of its flowers.
2. n. A plant of the genus Acacia.
3. n. The popular name of several plants of other genera. The green-barked acacia of Arizona is Parkinsonia Torreyana. False and bastard acacia are names sometimes applied to the locust-tree, Robinia Pseudacacia. The rose or bristly acacia is Robinia hispida. The name three-thorned acacia is sometimes given to the honey-locust, Gleditschia triacantha.
4. n. In medicine, the inspissated juice of several species of Acacia, popularly known as gum arabic (which see, under gum). A name given by antiquaries to an object resembling a roll of cloth, seen in the hands of consuls and emperors of the Lower Empire as represented on medals. It is supposed to have been unfurled by them at festivals as a signal for the games to begin.

Wiktionary

1. n. loosely Any of several related trees, such as the locust.
2. n. A light to moderate greenish yellow with a hint of red. . acacia colour:    
3. n. history, classical studies A roll or bag, filled with dust, borne by Byzantine emperors, as a memento of mortality. It is represented on medals.

GNU Webster's 1913

1. n. (Antiq.) A roll or bag, filled with dust, borne by Byzantine emperors, as a memento of mortality. It is represented on medals.
2. n. A genus of leguminous trees and shrubs. Nearly 300 species are Australian or Polynesian, and have terete or vertically compressed leaf stalks, instead of the bipinnate leaves of the much fewer species of America, Africa, etc. Very few are found in temperate climates.
3. n. (Med.) The inspissated juice of several species of acacia; -- called also gum acacia, and gum arabic.

WordNet 3.0

1. n. any of various spiny trees or shrubs of the genus Acacia