Definition of “alum” - English Dictionary

british dictionary

“alum” in British English

See all translations

alumnoun [ U ]

uk /ˈæl.əm/ us /ˈæl.əm/ specialized

a chemical substance containing aluminium used in dyeing (= changing the colour of something) and as an astringent (= substance that causes skin to tighten)

(Definition of “alum” from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)