cel·loi·din (s?-loid?n)n. A pure form of nitrocellulose in which specimens for microscopic examination are embedded.[cell(ulose) + -oid + -in.]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.celloidin (s??l??d?n) n (Biochemistry) a nitrocellulose compound derived from pyroxylin, used in a solution of alcohol and ether for embedding specimens before cutting sections for microscopy[C20: from cellulose + -oid + -in]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014cel?loi?din (s??l?? d?n) n. a concentrated form of pyroxylin used to embed tissues for cutting and microscopic examination. [1880?85; cell (ulose) + -oid + -in1] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.