lithify (?l???fa?) vb (tr) , -fies, -fying or -fiedto turn into rockCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014lith?i?fy (?l?? ??fa?) v. -fied, -fy?ing. v.t. 1. to change (sediment) to stone or rock. v.i. 2. to become lithified. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.