• synonyms

roche alum

noun Chemistry.
  1. an alumlike substance derived from alunite.
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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. 2018