A triangular sail set on the forestay of a sailing vessel.
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.
forestaysail(fɔːˈsteɪˌseɪl; nautical fɔːˈsteɪsəl)
(Nautical Terms) nautical the triangular headsail set aftermost on a vessel
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
fore•stay•sail(ˌfɔrˈsteɪˌseɪl, ˌfoʊr-; Naut. -səl)
a triangular sail set on a forestay.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.