disloyal
adjectiveUK /dɪsˈlɔɪəl/
US /dɪsˈlɔɪəl/
Not staying true to a friend or a promise.
The knight was disloyal and told the king's secret to the enemy.
RELATED WORDS
OTHER MEANINGS
2. Failing to support your country or group.
He was accused of being disloyal to his team by helping the other side.
3. Breaking a promise to someone who trusted you.
She felt disloyal when she forgot her best friend's birthday.
4. Not faithful to a ruler or leader.
The disloyal soldier left his post during the night.