Disloyal means not faithful or true to someone or something you're supposed to support. A disloyal friend might share your secrets with others or abandon you when you need help. A disloyal teammate might refuse to play hard when their team needs them most.

The word captures a specific kind of betrayal: breaking trust with people or groups you have a connection to. A soldier who turns against their country is disloyal. An employee who secretly works for a competitor while still on the payroll is disloyal. In stories, disloyal characters often switch sides or reveal plans to enemies.

Disloyalty hurts because it violates an expectation of faithfulness. When you join a team, make a friend, or become part of a family, there's an understanding that you'll stick together through challenges. A disloyal person breaks that understanding.

The opposite is loyal: staying true and supportive even when it's difficult or inconvenient. While everyone makes mistakes or disappoints others, being disloyal means deliberately choosing to betray a trust or commitment. It's one of the quickest ways to destroy relationships and lose people's respect.