common alder com·mo·nal·der uncommon noun 1. medium-sized tree with brown-black bark and woody fruiting catkins; leaves are hairy beneath Synonymscommon alderEuropean black alderAlnus glutinosaAlnus vulgaris Related words Broader terms alder Parts Alnus WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.
