titanium dioxiden. A white powder, TiO2, used as an exceptionally opaque white pigment.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.titanium dioxide n (Elements & Compounds) a white insoluble powder occurring naturally as rutile and used chiefly as a pigment of high covering power and durability. Formula: TiO2. Also called: titanium oxide, titanic oxide or titania Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014tita?nium diox?ide n. a white water-insoluble powder, TiO2, used in white pigments and plastics. [1920?25] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.