What is Cumulative?

Legal Definition
Forming a heap; additional; as, cumulative evidence, or that which goes to prove the same point which has been established by other evidence. Cumulative legacy, or accumulative legacy, is a second bequest, given by the same testator to the same legatee. 2 Rop. Log. 19,. See 1 Saund. 134, n. 4; Remedy.
-- Bouviers Law Dictionary
Legal Definition
Additional; heaping up; increasing; forming an aggregate. The word signifies that two things are to be added together, instead of one being a repetition or in substitution of the other. People v. Superior Court, 10 Wend. (N. Y.) 285; Regina v. Eastern Archipelago Co., 18 Eng. Law A Eq. 183.
See also
-- Black's Law Dictionary
Legal Definition
Adding to; by way of increase.
-- Ballentine's Law Dictionary