ISAabbr. Industry Standard ArchitectureAmerican 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.ISA abbreviation for 1. (Aeronautics) International Standard Atmosphere 2. (Aeronautics) Interim Standard Atmosphere ISA (?a?s?) n acronym for (Banking & Finance) individual savings account: a tax-free savings scheme introduced in Britain in 1999Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Isa. Isaiah. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.