sail·boat (s?l?b?t?)n. A small boat propelled partially or wholly by sail.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.sail?boat (?se?l?bo?t) n. a boat having sails as its principal means of propulsion. [1790?1800] sail?boat`er, n. sail?boat`ing, n. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.