What does "cumulative" mean?

Cumulative: (Law) (a) Tending to prove the same point to which other evidence has been offered; -- said of evidence. (b) Given by same testator to the same legatee; -- said of a legacy. Bouvier. Wharton. Cumulative action (Med.), that action of certain drugs, by virtue of which they produce, when administered in small doses repeated at considerable intervals, the same effect as if given in a single large dose. -- Cumulative poison, a poison the action of which is cumulative. -- Cumulative vote or system of voting (Politics), that system which allows to each voter as many votes as there are persons to be voted for, and permits him to accumulate these votes upon one person, or to distribute them among the candidates as he pleases.