- 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 most common form is potash alum (potassium aluminum sulfate), KAl(SO)12HO
- aluminum sulfate: an erroneous use
Origin of alumMiddle English and amp; Old French ; from Classical Latin alumen, alum: for Indo-European base see ale
Informal an alumnus or alumna
Any of various double sulfates of a trivalent metal such as aluminum, chromium, or iron and a univalent metal such as potassium or sodium, especially hydrous aluminum potassium sulfate, AlK(SO4)2·12H2O, widely used in industry as clarifiers, hardeners, and purifiers and medicinally as topical astringents and styptics.
Origin of alumMiddle English, from Old French, from Latin al&umacron;men.
An alumna or alumnus.
- An astringent salt, usually occurring in the form of pale crystals, much used in the dyeing and tanning trade and in certain medicines, and now understood to be a double sulphate of potassium and aluminium (K2SO4.Al2(SO4)3.24H2O). [from 14th c.]
- (chemistry) Any similar double sulphate in which either or both of the potassium and aluminium is wholly or partly replaced by other univalent or tervalent cations. [from 17th c.]
(third-person singular simple present alums, present participle aluming, simple past and past participle alumed)
- (US) A graduate of a university or other institution.