periselene vs periapsis

periselene and periapsis both are nouns.

Word	Noun	Adjective	Verb	Adverb
periselene	Yes	No	No	No
periapsis	Yes	No	No	No

As nouns, periapsis is a hypernym of periselene; that is, periapsis is a word with a broader meaning than periselene:

periselene: periapsis in orbit around the moon
periapsis: (astronomy) the point in an orbit closest to the body being orbited

Other hypernyms of periselene include point of periapsis.

periselene (noun)	periapsis (noun)
periapsis in orbit around the moon	(astronomy) the point in an orbit closest to the body being orbited