blue corn means: Blue-gray corn, a variety of corn that has blue-gray kernels. This corn was originally grown in the Southwest by Pueblo Indians. Dried and ground blue corn tastes better than yellow cornmeal. (in Cooking Dictionary)

What else does blue corn mean?

Type of corn flour (Zea mays var. amylacea) Contains blue or white kernels. They can be used as flour, meal, or as a substitute for wheat in tortillas. (in Merlin Dictionary)