I am not a huge food/scientists/knowledge person, but I do know that there is corn starch. So going based off just that name, and not a lot else to go by I would think that means corn is in fact a starch. Maybe it gets turned into a starch, or is used to make it, I am not sure.
While there is a product called corn starch - a white powder that is used in cooking to thicken sauces, the corn itself is a grain and corn starch is one of the many ways that corn can be processed into a type of food. Corn can also be consumed directly, as corn meal and in many other forms. Corn can also be used to produce eco-friendly fuel in the form of ethanol, but none of this changes what corn is in the first place, a grain product.