the word "tufa" entered english in the late 18th century from italian, where "tufo" denotes a porous rock. the italian term itself derives from the latin "tōfus," which referred to a soft, porous stone. this latin word is believed to be of pre-latin, possibly oscan or sabine, origin, reflecting the local volcanic geology of italy. the modern english usage has narrowed specifically to a lightweight, porous limestone formed by the action of mineral-laden water, distinguishing it from the harder, volcanic tuff, which shares a similar etymological ancestry.

this word is a loanword adopted as a single, unanalyzable unit in modern english.