falls vs perigonium

falls and perigonium both are nouns.

Word	Noun	Adjective	Verb	Adverb
falls	Yes	No	No	No
perigonium	Yes	No	No	No

As nouns, perigonium is a hypernym of falls; that is, perigonium is a word with a broader meaning than falls:

falls: the petals or sepals of a flower that bend downward (especially the outer perianth of an iris)
perigonium: collective term for the outer parts of a flower consisting of the calyx and corolla and enclosing the stamens and pistils

Other hypernyms of falls include chlamys, floral envelope, perianth, perigone.

falls (noun)	perigonium (noun)
a steep descent of the water of a river	collective term for the outer parts of a flower consisting of the calyx and corolla and enclosing the stamens and pistils
the petals or sepals of a flower that bend downward (especially the outer perianth of an iris)