From WordNet (r) 2.0 (August 2003) [wn]:
whitening
n : changing to a lighter color [syn: lightening]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Whiten \Whit"en\, v. i. [imp. & p. p. Whitened; p. pr. & vb.
n. Whitening.] [OE. whitenen; cf. Icel. hv[imac]tna.]
To grow white; to turn or become white or whiter; as, the
hair whitens with age; the sea whitens with foam; the trees
in spring whiten with blossoms.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Whitening \Whit"en*ing\, n.
1. The act or process of making or becoming white.
[1913 Webster]
2. That which is used to render white; whiting. [R.]
[1913 Webster]
Whitening stone, a sharpening and polishing stone used by
cutlers; also, a finishing grindstone of fine texture.
[1913 Webster]