[ 'aləm ]
■ noun Chemistry
1》 (also potash ~ ) a colourless astringent compound which is a hydrated double sulphate of ~inium and potassium, used in solution in dyeing and tanning.
2》 any of a series of analogous compounds of other metals.
Origin
ME: via OFr. from L. ~en , ~in- , related to aluta 'tawed leather'.