1350–1400;Middle Englishmenstruall < Latinmēnstruālis having monthly courses, equivalent to mēnstru(a) monthly courses (noun use of neuter plural of mēnstruus monthly; mēnstr- (see semester) + -uus adj. suffix, probably on the model of annuusannual) + -ālis-al1
Related formsin·ter·men·stru·al, adjectivepost·men·stru·al, adjectivepre·men·stru·al, adjectivepre·men·stru·al·ly, adverb
also pre-menstrual, 1865, from pre- + menstrual. Premenstrual syndrome (1971) earlier was premenstrual tension (1928).
late 14c., "pertaining to menses," also (in astronomy) "monthly," from Old French menstruel, from Latin menstrualis "monthly," especially "of or having monthly courses," from menstruus "of a month, every month, monthly, pertaining to a month," from mensis "month" (see moon (n.)).