Meaning

noun fine powdery foodstuff obtained by grinding and sifting the meal of a cereal grain

verb cover with flour

verb convert grain into flour

originSpelled (until about 1830) and meaning flower in the sense of flour being the "finest portion of ground grain" (compare French fleur de farine, fine fleur). Doublet of fleur, flor, and flower. Partially displaced native meal. The U.S. standard of identity comes from 21CFR137.105.

Etymology from Wiktionary, CC BY-SA 3.0