What is the meaning of Alum?

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).

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.

To steep in, or otherwise impregnate with, a solution of alum; to treat with alum.

A past attendee or graduate (of any gender) of a college, university or other educational institution.

wither

livid

bruise

coir for washing kitchen utensils, made from synthetic fibers with a rough texture

seven-eyed boil

Romanization of ꦲꦭꦸꦩ꧀

A plant, the comfrey

dative singular of alus

Alternative form of alym

dative plural of āl

alum

Source: wiktionary.org