chal·ced·o·ny also cal·ced·o·ny (k?l-s?d?n-?)n. pl. chal·ced·o·nies also cal·ced·o·nies A translucent to transparent milky or grayish quartz with distinctive microscopic crystals arranged in slender fibers in parallel bands.[Late Latin chalc?donius, from Greek khalk?d?n, a mystical stone (Revelation 21:19), perhaps from Khalk?d?n, Chalcedon.]chal?ce·don?ic (k?l?s?-d?n??k) adj.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.chalcedony (kæl?s?d?n?) or calcedonyn, pl -nies (Minerals) a microcrystalline often greyish form of quartz with crystals arranged in parallel fibres: a gemstone. Formula: SiO2[C15: from Late Latin chalc?d?nius, from Greek khalk?d?n a precious stone (Revelation 21:19), perhaps named after Khalk?d?n Chalcedon, town in Asia Minor] chalcedonic adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014chal?ced?o?ny (kæl?s?d n i, ?kæl s??do? ni) n., pl. -nies. a microcrystalline translucent variety of quartz, often milky or grayish. [1275?1325; Middle English calcedonie