alum

noun

1. a white crystalline double sulfate of aluminum: the ammonium double sulfate of aluminum

Definition categories: substance, aluminium, aluminum

2. a white crystalline double sulfate of aluminum: the potassium double sulfate of aluminum

Definition categories: substance, aluminium, aluminum

3. a person who has received a degree from a school (high school or college or university)

Similar word(s): alumna, alumnus, grad, graduate

Definition categories: person, bookman, scholar, student

4. a double sulphate of aluminum and potassium that is used as an astringent (among other things)

Definition categories: man–made, astringent, styptic

verb

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