cocoa (n.)

"brown powder produced by grinding roasted seeds of the cacao, an American evergreen tree," 1788, originally the seeds themselves (1707), corruption (by influence of coco) of cacao. The confusion with coco was already underway in English when the printers of Johnson's dictionary ran together the entries for coco and cocoa, after which it has never been undone. Cocoa has been the regular spelling from c. 1800.