Source : Webster's Revised Unabridged Dictionary (1913)

Contributory \Con*trib"u*to*ry\, n.; pl. {Contributories}.
   One who contributes, or is liable to be called upon to
   contribute, as toward the discharge of a common indebtedness.
   --Abbott.

Contributory \Con*trib"u*to*ry\, a.
   Contributing to the same stock or purpose; promoting the same
   end; bringing assistance to some joint design, or increase to
   some common stock; contributive. --Milton.

         Bonfires of contributory wood.           --Chapman.

   {Contributory negligence} (Law), negligence by an injured
      party, which combines with the negligence of the injurer
      in producing the injury, and which bars recovery when it
      is the proximate cause of the injury. --Wharton.

Source : WordNet®

contributory
     adj : tending to bring about; being partly responsible for;
           "working conditions are not conducive to productivity";
           "the seaport was a contributing factor in the growth of
           the city"; "a contributory factor" [syn: {conducive}, {contributing(a)},
            {contributive}, {tributary}]