alum Hear it!

alum1 definition

alum (al′əm)

noun

  1. a double sulfate of a monovalent metal or radical (as sodium, potassium, or ammonium) with a trivalent metal (as aluminum, iron, or chromium): it is used as an astringent, as an emetic, and in the manufacture of baking powders, dyes, and paper: the commonest form is potash alum (potassium aluminum sulfate), KAl(SO)·12HO
  2. aluminum sulfate: an erroneous use

Etymology: ME & OFr < L alumen, alum: for IE base see ale

alum2 definition

☆ alum (ə lum′)

noun

Informal an alumnus or alumna

Webster's New World College Dictionary Copyright © 2009 by Wiley Publishing, Inc., Cleveland, Ohio.
Used by arrangement with John Wiley & Sons, Inc.

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