corn vs popcorn

corn and popcorn both are nouns.

Word	Noun	Adjective	Verb	Adverb
corn	Yes	No	Yes	No
popcorn	Yes	No	No	No

As nouns, popcorn is a hyponym of corn; that is, popcorn is a word with a more specific, narrower meaning than corn:

Other hyponyms of corn include green corn, sweet corn, hominy.

As nouns, popcorn is a hyponym of corn; that is, popcorn is a word with a more specific, narrower meaning than corn:

corn: 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
popcorn: corn having small ears and kernels that burst when exposed to dry heat

corn (noun)	popcorn (noun)
something sentimental or trite	small kernels of corn exploded by heat
ears of corn that can be prepared and served for human food	corn having small ears and kernels that burst when exposed to dry heat
whiskey distilled from a mash of not less than 80 percent corn
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
(Great Britain) any of various cereal plants (especially the dominant crop of the region--wheat in Great Britain or oats in Scotland and Ireland)
the dried grains or kernels or corn used as animal feed or ground for meal
a hard thickening of the skin (especially on the top or sides of the toes) caused by the pressure of ill-fitting shoes

corn (verb)	popcorn (verb)
preserve with large-grained rock salt
feed (cattle) with corn