menses vs catamenia

menses and catamenia both are nouns.

Word	Noun	Adjective	Verb	Adverb
menses	Yes	No	No	No
catamenia	Yes	No	No	No

As nouns, menses and catamenia are synonyms defined as:

menses and catamenia: the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause

Other synonyms of menses include flow, menstruation, menstruum, period.

menses (noun)	catamenia (noun)
the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause	the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause