What is the Latin word for touch-stone?

The usual Latin words for “touch-stone” are cōticula, lēx, norma. The right choice depends on the sense; see the distinctions below.

English → Latin

“touch-stone” in Latin

cōticulaa touchstone; a small stone mortar for medical use lēxthe legal machinery of a state, the law; a law, statute, bill; the laws regarded as a body, the constitution normaa carpenter’s square; a norm, standard (rule, precept)

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

touch-stone

PROP., coticula: lapis Lydius (Plin.); “schistus Lydius (Linn.).

Figuratively, obrussa alicujus rei (Cic., Sen.); lex, norma, qua spectetur, ad quam exigatur, aliquid. To apply a touch-stone to anything, aliquid ad obrussam exigere (Sen.): this is a touch-stone for anything, haec est alicujus rei obrussa (Sen.).

Quick answer

What is the Latin word for touch-stone?: The usual Latin words for “touch-stone” are cōticula, lēx, norma. 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.