from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A gray mineral, chiefly K2Al3(OH)6(SO4)3, used in making alum and fertilizer.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A gray, water-soluble mineral, potassium aluminium sulphate; the natural source of alum, KAl3(SO4)2(OH)6.
from the GNU version of the Collaborative International Dictionary of English
- n. Alum stone.
from The Century Dictionary and Cyclopedia
- n. Same as alum-stone.
French, from alun, alum, from Latin alūmen.(American Heritage® Dictionary of the English Language, Fourth Edition)
From its earlier name aluminilite, named in 1824. (Wiktionary)