1. To put food in boiling water for a few seconds in order to loosen the skin or to scald food briefly, as before freezing it or as a preliminary stage in preparing a dish for eating: Marilyn followed the directions on the package and so she blanched the peaches briefly before peeling them.
2. To suddenly become pale or to turn white: Sam's face blanched at the mention of Shirley's name.

Quentin's face blanched in terror when he suddenly heard the big dog barking at him from behind the fence next to the sidewalk.
3. To grow vegetables, especially celery and endive, in unilluminated conditions in order to whiten the stems and to improve their flavor: The farmer renovated the barn in order to have a darkened area necessary to blanch the crops he had growing there.
4. Etymology: from about 1398, which came from Old French blanchir, "to whiten"; from blanc, "white".

Originally "to remove the hull of (almonds, etc.) by soaking". The sense of "to turn white" is from about 1768.