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, such as Lancashire owler, which is partly from Norse), from Proto-Germanic *aliso (cognates: Old Norse ölr, Danish elle, Swedish al, Dutch els, German erle), from *el-, the ancient PIE name of the tree (cognates: Russian olicha, Polish olcha, Latin alnus, Lithuanian alksnis).