on the rag prepositional phrase2 •(vulgar, offensive) Menstruating.She herself had begun menstruation shortly after her eleventh birthday and had gone to the head of the stairs to yell down excitedly: "Hey, Mum, I'm on the rag!" — 1974 •(vulgar, offensive) In a bad mood; angry or irritable.On the rag, in a bad mood.—College males, Arizona. I had a lousy time last night because she was on the rag. — 1967
