The Collaborative International Dictionary of English v.0.48:

acetaminophen \acetaminophen\ n.
   1. a white crystalline compound (HO.C6H4.NH.CO.CH3) used as
      an analgesic and also as an antipyretic. It has molecular
      weight 151.16. It is the active ingredient in the
      commercial analgesics Tylenol and Datril.

   Syn: p-hydroxyacetanilide, p-acetamidophenol,
        N-acetyl-p-aminophenol, paracetamol,
        N-(4-hydroxyphenyl)acetamide

   Note: It is sold under many trade names, and has been one of
         the most popular analgesics in the late 20th century.
         It is used in place of aspirin by people in whom
         aspirin causes undesirable side effects, such as
         stomach irritation or stomach bleeding.
         [PJC]