Alchemy

Alchemy is defined as "1) A medieval chemical philosophy having as its asserted aims the transmutation of base metals into gold, the discovery of the panacea, and the preparation of the elixir of longevity.  2) A seemingly magical power or precess of transmuting: 'He wondered by what alchemy it was changes, so that what sickened him one hour, maddened him with hunger the next' (Marjorie K. Rawlings)."  

The origin of the word alchemy comes originally from the Greek word Khemia from Egypt.  Late Greek changed the word to khemeia, khumeia.  From there, the Arabic language turned the word into al-kimiya, al- meaning the and kimiya meaning chemistry.  Medieval Latin changed the word to alchymia, then Old French alquemie, to Middle English alkamie, and finally to it's current from, alchemy.  

Source:  American Heritage Dictionary 4th Edition