The Collaborative International Dictionary of English v.0.48:
Blanch \Blanch\ (bl[.a]nch), v. t. [imp. & p. p. Blanched
(bl[.a]ncht); p. pr. & vb. n. Blanching.] [OE. blanchen,
blaunchen, F. blanchir, fr. blanc white. See Blank, a.]
1. To take the color out of, and make white; to bleach; as,
to blanch linen; age has blanched his hair.
2. (Gardening) To bleach by excluding the light, as the
stalks or leaves of plants, by earthing them up or tying
3. (Confectionery & Cookery)
(a) To make white by removing the skin of, as by scalding;
as, to blanch almonds.
(b) To whiten, as the surface of meat, by plunging into
boiling water and afterwards into cold, so as to
harden the surface and retain the juices.
4. To give a white luster to (silver, before stamping, in the
process of coining.).
5. To cover (sheet iron) with a coating of tin.
6. Fig.: To whiten; to give a favorable appearance to; to
whitewash; to palliate.
Blanch over the blackest and most absurd things.
Syn: To Blanch, Whiten.
Usage: To whiten is the generic term, denoting, to render
white; as, to whiten the walls of a room. Usually
(though not of necessity) this is supposed to be done
by placing some white coloring matter in or upon the
surface of the object in question. To blanch is to
whiten by the removal of coloring matter; as, to
blanch linen. So the cheek is blanched by fear, i. e.,
by the withdrawal of the blood, which leaves it white.