The Collaborative International Dictionary of English v.0.48:

Quinone \Qui"none\, n. [Quinine + ketone.] (Chem.)
   A crystalline substance, C6H4O2 (called also
   benzoketone), first obtained by the oxidation of quinic
   acid and regarded as a double ketone; also, by extension, any
   one of the series of which quinone proper is the type.
   [Written also chinone, kinone.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

quinone
    n 1: any of a class of aromatic yellow compounds including
         several that are biologically important as coenzymes or
         acceptors or vitamins; used in making dyes [syn: quinone,
         benzoquinone]