fore-and-aft sailn. A sail set more or less parallel to the keel of a vessel, attached to a mast or stay at its foremost edge and designed to catch the wind on either surface.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.