What is the Latin word for mill-stone?

The usual Latin words for “mill-stone” are mola, pūmex. The right choice depends on the sense; see the distinctions below.

English → Latin

“mill-stone” in Latin

molamillstone; mill; ground meal pūmexa pumice stone; pumice; any porous rock

Riddle & Arnold A Copious and Critical English–Latin Lexicon, 1864

mill-stone

lapis molaris (the kind of stone used for mill-stones, pyrites, silex, pumex; “a volcanic trachyte or porous lava,” Dictionary of Antiquities): mola (each mill had two such molae; of which the upper was catillus; the lower meta). Proverbially, to see through a mill-stone, lynceum esse: oculos acres atque acutos habere.

Quick answer

What is the Latin word for mill-stone?: The usual Latin words for “mill-stone” are mola, pūmex. The right choice depends on the sense; see the distinctions below.

Entry from J. E. Riddle & T. K. Arnold, A Copious and Critical English–Latin Lexicon (rev. C. Anthon, New York: Harper, 1864), digitised by Fergus J. P. Walsh, CC BY-SA 4.0; Latin markup adapted by latindictionary.co.