Source : Webster's Revised Unabridged Dictionary (1913)

Go \Go\, n.
   1. Act; working; operation. [Obs.]

            So gracious were the goes of marriage. --Marston.

   2. A circumstance or occurrence; an incident. [Slang]

            This is a pretty go.                  --Dickens.

   3. The fashion or mode; as, quite the go. [Colloq.]

   4. Noisy merriment; as, a high go. [Colloq.]

   5. A glass of spirits. [Slang]

   6. Power of going or doing; energy; vitality; perseverance;
      push; as, there is no go in him. [Colloq.]

   7. (Cribbage) That condition in the course of the game when a
      player can not lay down a card which will not carry the
      aggregate count above thirty-one.

   {Great go}, {Little go}, the final and the preliminary
      examinations for a degree. [Slang, Eng. Univ.]

   {No go}, a failure; a fiasco. [Slang] --Thackeray.

   {On the go}, moving about; unsettled. [Colloq.]

Source : WordNet®

on the go
     adj : (of a person) very busy and active; "is always on the go"
           [syn: {on the go(p)}]