xys·ter (z?s?t?r)n. A surgical instrument for scraping bones.[Greek x?st?r, scraper, from x?ein, to scrape.]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.xyster (?z?st?) n (Surgery) a surgical instrument for scraping bone; surgical rasp or file[C17: via New Latin from Greek: tool for scraping, from xuein to scrape, make smooth]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014