1. not faithful or devoted to a person, group, country, or cause; betraying trust or allegiance

Examples

• The disloyal employee sold company secrets to competitors.
• She felt it would be disloyal to criticize her friend in public.
• The general was accused of being disloyal to his country.
• His disloyal behavior cost him the trust of his teammates.
• Many considered switching parties to be a disloyal act.
• The disloyal servant revealed the family’s private affairs.