roche alum

[ rohch ]
/ roʊtʃ /

noun Chemistry.

an alumlike substance derived from alunite.

Origin of roche alum

1400–50; roche cliff, rocky height (now obsolete), late Middle English (see rock1); apparently partial translation of Middle French alum en roque, alun de roche
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019