
Cake flour is very finely ground soft wheat used to make tender, fine-textured cakes. It is bleached with chlorine gas, which, besides whitening the flour, also makes it slightly acidic. This acidity makes cakes set faster and have a finer texture.
Found on
http://whatscookingamerica.net/Glossary/C.htm

(from the article `flour`) ...flour, a starch-free, high-protein, whole wheat flour; all-purpose flour, refined (separated from bran and germ), bleached or unbleached, and ...
Found on
http://www.britannica.com/eb/a-z/c/5

finely ground flour made from soft wheat suitable for making cakes; it is very low in protein (6-8%)
Found on
https://thebakersalmanac.com/ultimate-baking-glossary/

Fine-textured, silky flour milled from soft wheat, with a low protein content for making cakes, cookies, pastries and some breads. Learn more from Texas Wheat ,
Found on
https://www.homebaking.org/glossary/
No exact match found.