mont·​mo·​ril·​lon·​ite ˌmänt-mə-ˈri-lə-ˌnīt How to pronounce montmorillonite (audio) -ˈrē-ə-ˌnīt How to pronounce montmorillonite (audio)
: a soft clayey water-absorbent mineral that is a hydrous aluminum silicate
montmorillonitic adjective

Example Sentences

Recent Examples on the Web The clay used in cat litter is a natural soil component made of minerals—either calcium montmorillonite or the clumping sodium bentonite. Lorraine Wilde, Treehugger, 23 Jan. 2023

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'montmorillonite.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History


French, from Montmorillon, commune in western France

First Known Use

1854, in the meaning defined above

Time Traveler
The first known use of montmorillonite was in 1854

Dictionary Entries Near montmorillonite

Cite this Entry

“Montmorillonite.” Dictionary, Merriam-Webster, Accessed 29 Jan. 2023.

More from Merriam-Webster on montmorillonite

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