Doctor

Milk and water, with a little rum, and some nutmeg; also the name of a composition used by distillers, to make spirits appear stronger than they really are, or, in their phrase, better proof.
to adulterate or drug liquor; to poison, to hocus; also to falsify accounts. A publican who sells bad liquors is said to keep the doctor  in his cellars. On board ship the cook is always termed “the doctor.”—See cook.