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).
Other meanings
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.
A past attendee or graduate (of any gender) of a college, university or other educational institution.
Related words
- unalumed
- alumiferous
- alumium
- alumroot
- alumstone
- carmalum
- hemalum
- alum cake
- alum earth
- alumed
- plumose alum
- alumina
Word history
From Latin "alūmen".
Where this comes from
This definition is adapted from “alum” on Wiktionary, by its contributors, published under CC BY-SA 4.0. This page is published under the same licence.