We use cookies to enhance your experience on our website. By continuing to use our website, you are agreeing to our use of cookies. You can change your cookie settings at any time. Find out more

Subscriber login

Library card login

Other

X Close menu

Dictionary Language resources

alum

Pronunciation: /ˈaləm/

(also potash alum)

Definition of alum

noun

[mass noun] Chemistry

a colourless astringent compound which is a hydrated double sulphate of aluminium and potassium, used in solution in dyeing and tanning.
- Chemical formula: AlK(SO₄)₂.12H₂O
[count noun] any of a number of analogous crystalline double sulphates of a monovalent metal (or group) and a trivalent metal: artificially grown crystals of one of the alums