/ (ˈpɜːspɛks) /
trademark any of various clear acrylic resins, used chiefly as a substitute for glass
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for perspex
1935, trade name in Britain for what in the U.S. is called Plexiglas or Lucite, irregularly formed from Latin perspect-, past participle stem of perspicere "look through, look closely at" (see perspective).
Online Etymology Dictionary, © 2010 Douglas Harper