Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “alum”

alum

noun [U] uk   /ˈæl.əm/ specialized us  
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 Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of alum?
Add Cambridge dictionaries to your browser to your website

Word of the Day

debut

the occasion when someone performs or presents something to the public for the first time

Word of the Day

Come on – you can do it! Phrasal verbs with ‘come’.

by Liz Walter​,
November 19, 2014
As part of an occasional series on the tricky subject of phrasal verbs, this blog looks at ones formed with the verb ‘come’. If you are reading this blog, I’m sure you already know come from, as it is one of the first things you learn in class: I come from Scotland/Spain.

Read More 

silver splicer noun

November 17, 2014
informal a person who marries in later life Newly retired and now newlywed – rise of the ‘silver splicers’ Reaching pension age becomes a trigger to tie the knot as baby-boomers begin to redefine retirement

Read More