two-hitter vs baseball

two-hitter and baseball both are nouns.

Word	Noun	Adjective	Verb	Adverb
two-hitter	Yes	No	No	No
baseball	Yes	No	No	No

As nouns, baseball is a hypernym of two-hitter; that is, baseball is a word with a broader meaning than two-hitter:

two-hitter: a game in which a pitcher allows the opposing team only 2 hits
baseball: a ball game played with a bat and ball between two teams of nine players; teams take turns at bat trying to score runs

Other hypernyms of two-hitter include ball, baseball game.

two-hitter (noun)	baseball (noun)
a game in which a pitcher allows the opposing team only 2 hits	a ball game played with a bat and ball between two teams of nine players; teams take turns at bat trying to score runs
	a ball used in playing baseball