ironwood

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of numerous trees, such as the hornbeam and the hop hornbeam, that have very hard wood.
2. n. The wood of any of these trees.

Century Dictionary and Cyclopedia

1. n. One of numerous species of peculiarly hard-wooded trees, belonging to many orders and widely distributed. In North America the name commonly denotes Ostrya Virginica, the hop-hornbeam or leverwood; but also Bumelia lycioides(southern buckthorn), Carpinus Caroliniana (blue beech), Cyrilla racemiflora, Cliftonia ligustrina (titi, buckwheat-tree), Hypelate paniculata (inkwood), and Olneya Tesota. The black ironwood of the same territory is Condalia ferrea; the red, Reynosia latifolia; the white, Hypelate trifoliata. Of the other ironwoods may be mentioned the various species of the tropical genus Sideroxylon, the Indian Xylia dolabriformis, the Erythroxylon areolatum of Jamaica, and the Tasmanian Notelæa ligustrina. Several species of Diospyros (ebony) are called by the same name. Bastard ironwood is the West Indian Xanthoxylum Fagara (X. Pterota); also Trichilia hirta. The black ironwood of South Africa is Olea undulata, and the white is Toddalia lanceolata. Many of these woods are valuable in the arts for purposes requiring great firmness or high polish.
2. n. In Polynesia, Casuarina equisetifolia, a littoral tree with jointed leafless branches and very hard and heavy wood: used by the natives for making spears. See horsetail-tree and agoho.
3. n. A large tree of the myrtle family, Metrosideros lucida, yielding a very hard, strong, red wood, which is used for ship-building, spokes, hubs, and cross-ties for railways.

Wiktionary

1. n. countable Any of a number of tree species known for having a particularly solid wood.
2. n. uncountable The wood of any ironwood tree.

GNU Webster's 1913

1. n. (Bot.) A tree unusually hard, strong, or heavy wood.

WordNet 3.0

1. n. exceptionally tough or hard wood of any of a number of ironwood trees
2. n. medium-sized hop hornbeam of eastern North America
3. n. handsome East Indian evergreen tree often planted as an ornamental for its fragrant white flowers that yield a perfume; source of very heavy hardwood used for railroad ties
4. n. a small slow-growing deciduous tree of northern Iran having a low domed shape