noun
alum
An aluminum-based salt used as an astringent or in chemical treatment.
The technician adds alum during the water treatment demonstration.
Etymology
Latin alumen named the mineral substance alum. The English word preserves that material name for salts valued for their astringent properties and uses in processing other substances.
More examples
- The old recipe calls for a small quantity of alum.
- A labeled jar contains pale alum crystals.
- The exhibit describes the historical use of alum in dyeing.
Forms
alum · alums
Similar words
- astringent
- Names a functional category rather than this particular salt.