corn has 7 distinct synonyms spread across 4 of its 9 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
tall annual cereal grass bearing kernels on large ears: widely cultivated in America in many varieties; the principal cereal in Mexico and Central and South America since pre-Columbian times
the dried grains or kernels or corn used as animal feed or ground for meal
ears of corn that can be prepared and served for human food
(Great Britain) any of various cereal plants (especially the dominant crop of the region--wheat in Great Britain or oats in Scotland and Ireland)
whiskey distilled from a mash of not less than 80 percent corn
something sentimental or trite
“that movie was pure corn”
Synonyms, antonyms and the broader and narrower relations for corn come from Princeton University’s WordNet. Full sources and licences.