on

   1.drunk

   In a mild state:

    I shouldn't like to say how he was drunk... he was a little bit on like. (EDD)

   This use is obsolete except in the expression half on, where, as usual with drunkenness, the half equals the whole.

   2. pregnant

   Today in a phrase, such as four months on. In former use, tout court:

    I doubt she's on again, poor lass. (EDD — doubt means suspect)

   3.habitually using illegal narcotics

   A shortened form of on drugs:

   But a woman like that living a life like that, has got to be on. (Sanders, 1977)

   4. potentially promiscuous

   On in the sense, happening or going ahead:

    Those legs at the corner table might be on, but they could just be here for conversation. (Blacker, 1992 — the legs belonged to a female)