disloyal

/dɪsˈlɔɪəl/
adjective
  1. Not faithful or loyal to a person, group, or cause; betraying trust.
    • He considered switching teams to be disloyal to his original coach.
    • It felt disloyal to talk behind her best friend's back.
    • The soldier was accused of disloyal behavior for sharing secrets with the enemy.
Antonyms
What does "disloyal" mean? | whatsthatwordmean | whatsthatwordmean