alum: Meaning and Definition of

al•um

1. Also calleda crystalline solid, aluminum potassium sulfate, KSO&multiplydot;Al(SO)&multiplydot;24HO, 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 RSO&multiplydot;X(SO)&multiplydot;24HO, 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.

a•lum

1. an alumna or alumnus.

alum.

1. aluminum.