# bentonite

> English word · Noun · frequency rank #59,892

## Definitions
1. Any of several impure clay minerals consisting mostly of montmorillonite.
2. A porous clay formed by the decomposition of volcanic ash that swells 5 to 6 times its original volume in the presence of water.

## Etymology
From Benton + -ite, after the place where it was first mined: Fort Benton, Montana.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/bentonite