Noah Webster's New International Dictionary of the English Language

1. (adv.) Well rounded or filled out; full; fleshy; fat; as, a plump baby; plump cheeks.

2. (n.) A knot; a cluster; a group; a crowd; a flock; as, a plump of trees, fowls, or spears.

3. (v.) To grow plump; to swell out; as, her cheeks have plumped.

4. (v.) To drop or fall suddenly or heavily, all at once.

5. (v.) To give a plumper. See Plumper, 2.

6. (v. t.) To make plump; to fill (out) or support; -- often with up.

7. (v. t.) To cast or let drop all at once, suddenly and heavily; as, to plump a stone into water.

8. (v. t.) To give (a vote), as a plumper. See Plumper, 2.

9. (a. & v.) Directly; suddenly; perpendicularly.