am·y·loid·o·sis (?m??-loi-d??s?s)n. Any of a group of diseases or conditions characterized by the formation and deposition of amyloid in various organs and tissues of the body.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.amyloidosis (?æm?l???d??s?s) n (Pathology) pathol the deposition of amyloid in various tissues of the body, as occurs in certain chronic infectionsCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014