cel·lu·lase (s?l?y?-l?s?, -l?z?)n. Any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze the hydrolysis of cellulose.[cellul(ose) + -ase.]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.cellulase (?s?lj??le?z) n (Biochemistry) any enzyme that converts cellulose to the disaccharide cellobiose[C20: from cellulose + -ase]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014cel?lu?lase (?s?l y??le?s, -?le?z) n. any of several enzymes, produced primarily by fungi and bacteria, that catalyze the hydrolysis of cellulose. [1900?05] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.