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.

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.

(not in technical use) aluminum sulfate.

an alumna or alumnus.

aluminum.