black aldern.1. A Eurasian alder tree (Alnus glutinosa) that grows in wet soil and is naturalized in parts of North America.2. See winterberry.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.black? al?der n. 1. a holly, Ilex verticillata, of E and midwestern North America, bearing red fruit that remains through early winter. 2. a European alder, Alnus glutinosa, having a gray bark and sticky foliage. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.