cereal vs hot cereal

cereal and hot cereal both are nouns.

Word	Noun	Adjective	Verb	Adverb
cereal	Yes	Yes	No	No
hot cereal	Yes	No	No	No

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

Other hyponyms of cereal include Pablum, cold cereal, dry cereal.

cereal (noun)	hot cereal (noun)
a breakfast food prepared from grain	a cereal that is served hot
foodstuff prepared from the starchy grains of cereal grasses
grass whose starchy grains are used as food: wheat, rice, rye, oats, maize, buckwheat, millet

cereal (adjective)	hot cereal (adjective)
made of grain or relating to grain or the plants that produce it