Dictionary:

runagate

  (rŭn'ə-gāt')

1. A renegade or deserter.
2. A vagabond.

[Alteration of obsolete renegate, renegade (influenced by RUN and agate, on the way), from Middle English, from Medieval Latin renegātus. See renegade.]

noun

A person who has defected: apostate, defector, deserter, recreant, renegade, tergiversator, turncoat. Informal rat. See approach/retreat.