alder

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various deciduous shrubs or trees of the genus Alnus, native chiefly to northern temperate regions and having alternate simple toothed leaves and woody, conelike catkins.
• noun The wood of these plants, used in carvings and for making furniture and cabinets.

from The Century Dictionary.

• noun An old form of elder.
• The Middle English genitive plural of all.
• noun A shrub of the genus Fothergilla, of the southeastern United States.
• noun Alnus rhombifolia, of the western United States.
• noun The striped maple, Acer Pennsylvanicum.
• noun The popular name of shrubs and trees belonging to the genus Alnus, natural order Cupuliferæ.
• noun A name of species of other widely different genera, from their resemblance to true alders.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Bot.) A tree, usually growing in moist land, and belonging to the genus Alnus. The wood is used by turners, etc.; the bark by dyers and tanners. In the U. S. the species of alder are usually shrubs or small trees.
• noun An American species of holly (Ilex verticillata), bearing red berries.
• adjective obsolete Of all; -- used in composition.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of several trees or shrubs of the genus Alnus, belonging to the birch family.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun north temperate shrubs or trees having toothed leaves and conelike fruit; bark is used in tanning and dyeing and the wood is rot-resistant
• noun wood of any of various alder trees; resistant to underwater rot; used for bridges etc