Plump \Plump\, v. t. [imp. & p. p. {Plumped}; p. pr. & vb. n. {Plumping}.] 1. To make plump; to fill (out) or support; -- often with up. [1913 Webster] To plump up the hollowness of their history with improbable miracles. --Fuller. [1913 Webster] 2. To cast or let drop all at once, suddenly and heavily; as, to plump a stone into water. [1913 Webster] 3. To give (a vote), as a plumper. See {Plumper}, 2. [1913 Webster]