(1):

(a.) Of or pertaining to a menstruum.

(2):

(a.) Of or pertaining to the menses; as, menstrual discharges; the menstrual period.

(3):

(a.) Recurring once a month; monthly; gone through in a month; as, the menstrual revolution of the moon; pertaining to monthly changes; as, the menstrual equation of the sun's place.