Source : Webster's Revised Unabridged Dictionary (1913)

Accumulative \Ac*cu"mu*la*tive\, a.
   Characterized by accumulation; serving to collect or amass;
   cumulative; additional. -- {Ac*cu"mu*la*tive*ly}, adv. --
   {Ac*cu"mu*la*tive*ness}, n.

Source : WordNet®

accumulative
     adj 1: increasing by successive addition; "the benefits are
            cumulative"; "the eventual accumulative effect of
            these substances" [syn: {cumulative}]
     2: marked by acquiring or amassing; "we live in an accumulative
        society"