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

Examples of montmorillonite in a Sentence

Recent Examples on the Web Layers of clay — bentonite and montmorillonite, to be specific — are found beneath the ground, interspersed between layers of bedrock. Jack Flemming, Los Angeles Times, 13 July 2023 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 examples are programmatically compiled from various online sources to illustrate current usage of the word 'montmorillonite.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

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 23 Jul. 2024.

More from Merriam-Webster on montmorillonite

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!