hui·sache (w?-säch?, -sä?ch?)n. A thorny shrub (Acacia farnesiana) of tropical and subtropical America, having clusters of small fragrant yellow flowers that yield an essential oil used in perfumery. Also called sweet acacia.[American Spanish, from Nahuatl huixachi, thorny, thorny tree : huitztli, thorn + ixachi, much, abundant.]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.huisache (wi??s??t??) n (Plants) a thorny shrub or small tree of tropical or sub-tropical America, Acacia farnesia var farnesia, with clusters of fragrant yellow flower heads used in perfumery. Also called: cassie, opopanax, popinac(k), sweet acacia or sponge tree Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014