Rosemarie Ostler in Lapham’s Quarterly:
Corn offers an example of how English words evolved in America. Before 1492, the plant that Americans call corn (Zea mays) was unknown in England. The word corn was a general term for grain, usually referring to whichever cereal crop was most abundant in the region. For instance, corn meant wheat in England, but usually referred to oats in Ireland. When American corn came to Britain, it was named maize, the English version of mahiz, an Indigenous Arawakan word adopted by the Spanish. When the first colonists encountered it in North America, however, they almost always referred to it as corn or Indian corn, probably because it was the main cereal crop of the area.
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