|a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.|
|a fool or simpleton; ninny.|
mercaptopurine mer·cap·to·pu·rine (mər-kāp'tō-py&oobreve;r'ēn)
A purine analogue that acts as an antimetabolite by interfering with purine synthesis, used primarily in the treatment of acute leukemia.