junk food vs solid food

junk food and solid food both are nouns.

Word	Noun	Adjective	Verb	Adverb
junk food	Yes	No	No	No
solid food	Yes	No	No	No

As nouns, solid food is a hypernym of junk food; that is, solid food is a word with a broader meaning than junk food:

junk food: food that tastes good but is high in calories having little nutritional value
solid food: any solid substance (as opposed to liquid) that is used as a source of nourishment

Other hypernyms of junk food include food.

junk food (noun)	solid food (noun)
food that tastes good but is high in calories having little nutritional value	any solid substance (as opposed to liquid) that is used as a source of nourishment