renegade

Short definition from Wiktionary

Noun

1. 1
   An outlaw or rebel.
2. 2
   A disloyal person who betrays or deserts a cause, religion, political party, friend, etc.

Verb

1. 1
   To desert one's cause, or change one's loyalties; to commit betrayal.

Adjective

1. 1
   Deserting, treacherous, disloyal.
2. 2
   Unconventional, unorthodox.