SPFabbr. sun protection factorAmerican 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.SPF abbreviation for 1. (Telecommunications) sender policy framework: a mechanism designed to prevent an e-mail address being duplicated and used as a false address from which to send unsolicited e-mails 2. (Chemical Engineering) sun protection factor: an indicator of how effectively a sun cream, lotion, cosmetic, etc, protects the skin from the harmful rays of the sun: SPF 25. Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014SPF sun protection factor: the effectiveness of suntanning preparations in protecting the skin from ultraviolet radiation. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.