shredder

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One that shreds.
• noun A device used for shredding documents, often as a security measure to prevent unapproved persons from reading them.
• noun Slang One who rides a board in a board sport, such as snowboarding, especially in a fast manner featuring many quick turns.
• noun Slang One who plays fast solos on the electric guitar.

from The Century Dictionary.

• noun A machine for cutting into shreds or short slivers the stalks, leaves, and husks of ripe corn-plants in making stover or shredded fodder for cattle. It is a large and complicated power-machine resembling in general appearance a threshing-machine, and is often called a husker and shredder. The stalks of corn, with the ears, are fed to the machine, which removes and husks the ears, cuts the stalks into short pieces, shreds the stalks, leaves, and husks, cleans them from dust, and delivers the shredded product to a stacker or to a baling-press.
• noun A machine for shredding whole wheat into long filaments or shreds. It consists essentially of pairs of steel rolls, one having a finely fluted face, placed above a traveling conveyer. Prepared whole wheat is fed between each pair of rolls and is torn into long threads that fall upon the conveyer and are conveyed to cutting-knives which divide them into cakes ready for baking.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A machine that tears up objects into smaller pieces, especially a paper shredder or garbage shredder.
• noun computing A program that overwrites deleted data to prevent recovery.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a device that shreds documents (usually in order to prevent the wrong people from reading them)