[ahr-juh-ley-shuh s]
  1. Geology, Petrology. of the nature of or resembling clay; clayey.
  2. containing a considerable amount of clayey matter.

Origin of argillaceous

First recorded in 1725–35, argillaceous is from the Latin word argillāceus clayish. See argil, -aceous Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for argillaceous

Historical Examples of argillaceous

British Dictionary definitions for argillaceous


  1. (of sedimentary rocks and deposits) composed of very fine-grained material, such as clay, shale, etcCompare arenaceous (def. 1), rudaceous
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012