any N temperate betulaceous shrub or tree of the genus Alnus, having toothed leaves and conelike fruits. The bark is used in dyeing and tanning and the wood for bridges, etc because it resists underwater rot
any of several similar trees or shrubs
Word Origin for alder
Old English alor; related to Old High German elira, Latin alnus
tree related to the birch, Old English alor "alder" (with intrusive -d- added 14c.; the historical form aller survived until 18c. in literary English and persists in dialects, e.g. Lancashire owler, which is partly from Norse), from Proto-Germanic *aliso (cf. Old Norse ölr, Danish elle, Swedish al, Dutch els, German erle), from *el-, the ancient PIE name of the tree (cf. Russian olicha, Polish olcha, Latin alnus, Lithuanian alksnis).