ap·y·rase (?p??-r?s?, -r?z?)n. Any of various enzymes that catalyze the hydrolysis of ATP or ADP, producing AMP and inorganic phosphate and releasing energy.[a(denosine) + pyr(o)- + (phosphat)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.apyrase (?æp??re?z) nany of various enzymes that catalyse the hydrolysis of adenosine triphosphate, yielding a phosphate and energyCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014