alum
noun /ˈæləm/
/ˈæləm/
[uncountable]- a substance formed from aluminium and another metal, used, for example, to prepare leather and to change the colour of things
明矾,白矾(用于制革、印染等) 词源late Middle English: via Old French from Latin alumen, alumin- related to aluta ‘a kind of leather’.