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alum1

[al-uh m] /ˈæl əm/
noun, Chemistry
1.
Also called potash alum, potassium alum. a crystalline solid, aluminum potassium sulfate, K 2 SO 4 ⋅Al 2 (SO 4) 3 ⋅24H 2 O, used in medicine as an astringent and styptic, in dyeing and tanning, and in many technical processes.
2.
one of a class of double sulfates analogous to the potassium alum, as aluminum ammonium sulfate, having the general formula R 2 SO 4 ⋅X 2 (SO 4) 3 ⋅24H 2 O, where R is a univalent alkali metal or ammonium, and X one of a number of trivalent metals.
3.
(not in technical use) aluminum sulfate.
Origin
1275-1325
1275-1325; Middle English < Anglo-French < Latin alūmen; replacing Old English alefne, ælifnæ < Old Welsh (compare MWelsh elyf) < Latin alūmini- (stem of alūmen)

alum2

[uh-luhm] /əˈlʌm/
noun, Informal.
1.
an alumna or alumnus.
Origin
by shortening
Can be confused
alum, alumna, alumnae, alumni, alumnus (see usage note at alumnus)

alum.

Chemistry
1.
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples for alum
  • Soak in alum water to cover, allowing two teaspoons powdered alum to each quart of water.
  • Cover with alum water, allowing two teaspoons powdered alum to each quart of water.
  • alum treatment in shallow lakes for phosphorus inactivation may last for eight or more years.
  • alum treatment doubled the volume of anaerobically digested sludge produced.
British Dictionary definitions for alum

alum

/ˈæləm/
noun
1.
Also called potash alum. a colourless soluble hydrated double sulphate of aluminium and potassium used in the manufacture of mordants and pigments, in dressing leather and sizing paper, and in medicine as a styptic and astringent. Formula: K2SO4.Al2(SO4)3.24H2O
2.
any of a group of isomorphic double sulphates of a monovalent metal or group and a trivalent metal. Formula: X2SO4.Y2(SO4)3.24H2O, where X is monovalent and Y is trivalent
Word Origin
C14: from Old French, from Latin alūmen
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for alum
n.

late 14c., "whitish mineral salt used as an astringent, dye, etc.," from Old French alum, from Latin alumen "alum," literally "bitter salt," cognate with Greek aludoimos "bitter" and perhaps with English ale.

Online Etymology Dictionary, © 2010 Douglas Harper
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alum in Medicine

alum al·um (āl'əm)
n.
Any of various double sulfates of a trivalent metal such as aluminum or iron and a univalent metal such as potassium or sodium that are used as topical astringents and styptics.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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alum in Science
alum
  (āl'əm)   
Any of various crystalline double salts of a trivalent metal (such as aluminum, chromium, or iron) and a monovalent metal (such as potassium or sodium), especially aluminum potassium sulfate. Alum is widely used in industry as a hardener and purifier, and in medicine as an emetic and to stop bleeding.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Slang definitions & phrases for alum

alum

noun

An alumnus or alumna


The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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Related Abbreviations for alum

alum

  1. alumna
  2. alumnae
  3. alumni
  4. alumnus

alum.

aluminum
The American Heritage® Abbreviations Dictionary, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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6
9
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