SFX pl n 1. (Film) short for sound effects. See sound effect 2. (Film) short for special effects [C20: s(ound), s(pecial) + a phonetic respelling of effects]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014