[ ben-tn-ahyt ]
/ ˈbɛn tnˌaɪt /

noun Mineralogy.

a clay formed by the decomposition of volcanic ash, having the ability to absorb large quantities of water and to expand to several times its normal volume.

Origin of bentonite

1895–1900; named after Fort Benton, Montana; see -ite1
Related formsben·ton·it·ic [ben-tn-it-ik] /ˌbɛn tnˈɪt ɪk/, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for bentonite

  • Sodium sulphate and bentonite are two of the more recent mineral discoveries in North Dakota.

    North Dakota|Various

British Dictionary definitions for bentonite


/ (ˈbɛntəˌnaɪt) /


a valuable clay, formed by the decomposition of volcanic ash, that swells as it absorbs water: used as a filler in the building, paper, and pharmaceutical industries

Word Origin for bentonite

C19: from Fort Benton, Montana, USA, where found, + -ite 1
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