undescended testis vs orchis

undescended testis and orchis both are nouns.

Word	Noun	Adjective	Verb	Adverb
undescended testis	Yes	No	No	No
orchis	Yes	No	No	No

As nouns, orchis is a hypernym of undescended testis; that is, orchis is a word with a broader meaning than undescended testis:

undescended testis: a testis that fails to move into the scrotum as the male fetus develops
orchis: one of the two male reproductive glands that produce spermatozoa and secrete androgens

Other hypernyms of undescended testis include ball, ballock, bollock, egg, nut, testicle, testis.

undescended testis (noun)	orchis (noun)
a testis that fails to move into the scrotum as the male fetus develops	one of the two male reproductive glands that produce spermatozoa and secrete androgens
	any of various deciduous terrestrial orchids having fleshy tubers and flowers in erect terminal racemes