*nonone*

n. [ Nonane + -one, suffix denoting the third degree of unsaturation. ] (Chem.) 1. Any one of several metameric unsaturated hydrocarbons (C9H14) of the valylene series. [ archaic? ] [ 1913 Webster ]

2. Any of several isomeric ketones (C9H18O) conceptually derived from nonane by substituting an oxygen for two hydrogen atoms on one of the non-terminal carbon atoms. [ PJC ]