alum

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UK:*UK and possibly other pronunciationsUK and possibly other pronunciations/ˈæləm/US:USA pronunciation: IPA and respellingUSA pronuncation: IPA/ˈæləm/ ,USA pronunciation: respelling(Chem. aləm; Informal ə lum)



WordReference Random House Learner's Dictionary of American English © 2020
al•um1 /ˈæləm/USA pronunciation   n. [uncountable]
  1. Chemistrya white, crystal-like salt used in medicine, dyeing, and tanning.

a•lum2 /əˈlʌm/USA pronunciation   n. [countable] Informal.
  1. Informal Termsan alumna or alumnus.

WordReference Random House Unabridged Dictionary of American English © 2020
al•um1  (aləm),USA pronunciation n. [Chem.]
  1. ChemistryAlso called  potash alum, potassium alum. a crystalline solid, aluminum potassium sulfate, K2SO4·Al2(SO4)3·24H2O, used in medicine as an astringent and styptic, in dyeing and tanning, and in many technical processes.
  2. Chemistryone of a class of double sulfates analogous to the potassium alum, as aluminum ammonium sulfate, having the general formula R2SO4·X2(SO4)3·24H2O, where R is a univalent alkali metal or ammonium, and X one of a number of trivalent metals.
  3. Chemistry(not in technical use) aluminum sulfate.
  • Latin alūmini- (stem of alūmen)
  • OWelsh (compare MWelsh elyf)
  • Latin alūmen; replacing Old English alefne, ælifnæ
  • Anglo-French
  • Middle English 1275–1325

a•lum2  (ə lum),USA pronunciation n. [Informal.]
  1. Informal Termsan alumna or alumnus.
[by shortening]
alum., [Chem.]
  1. Chemistryaluminum.

Collins Concise English Dictionary © HarperCollins Publishers::
alum /ˈæləm/ n

  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
Etymology: 14th Century: from Old French, from Latin alūmen
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