whitening

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

• noun An agent used to make something white or whiter.
• noun The act or process of making white or whiter.

from The Century Dictionary.

• noun The act or process of making white.
• noun In leather manufacturing, the operation of cleaning and preparing the flesh side of a hide on a beam, preparatory to waxing.
• noun Tin-plating. See chemical plating, under plate, transitive verb
• noun Same as whiting.

from the GNU version of the Collaborative International Dictionary of English.

• noun The act or process of making or becoming white.
• noun rare That which is used to render white; whiting.
• noun a sharpening and polishing stone used by cutlers; also, a finishing grindstone of fine texture.

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

• noun a substance, such as a bleach, used to make something white or whiter
• noun the process of making something white or whiter

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

• noun changing to a lighter color