semifinalist vs rival

semifinalist and rival both are nouns.

Word	Noun	Adjective	Verb	Adverb
semifinalist	Yes	No	No	No
rival	Yes	Yes	Yes	No

As nouns, rival is a hypernym of semifinalist; that is, rival is a word with a broader meaning than semifinalist:

semifinalist: one of four competitors remaining in a tournament by elimination
rival: the contestant you hope to defeat

Other hypernyms of semifinalist include challenger, competition, competitor, contender.

semifinalist (noun)	rival (noun)
one of four competitors remaining in a tournament by elimination	the contestant you hope to defeat

semifinalist (adjective)	rival (adjective)
	as a rival in a competition

semifinalist (verb)	rival (verb)
	be the rival of, be in competition with
	be equal to in quality or ability