The tartaric acid or lees adhering to the sides of wine-casks, particularly of port-wine; an article of commerce; supertartrate of potass.
·noun Crude tartar; an acidulous salt from which cream of tartar is prepared. It exists in the juice...
Webster's Dictionary of the English Language
tartar, or lees of wine. N. and S. ...
A glossary of provincial and local words used in England by Francis Grose