To interfere means to get involved in something in a way that disrupts it or makes it harder to accomplish. When you're trying to concentrate on homework and your little brother keeps asking you questions, he's interfering with your work. When static interferes with a radio signal, it disrupts the sound and makes it hard to hear clearly.

Interference often isn't wanted or helpful. If two friends are trying to resolve an argument and a third person keeps jumping in with opinions, that person is interfering in something that doesn't concern them. In sports, interference happens when a player illegally blocks or disrupts an opponent, like in football when someone blocks a receiver who isn't anywhere near the ball.

The word carries a sense of butting in where you're not needed or wanted. Parents sometimes have to decide when to let kids work things out themselves and when a situation truly needs adult involvement. That's the difference between helping and interfering: help is welcome and makes things better, while interference gets in the way and makes things harder.

Scientists also use interfere to describe when two waves (like light or sound) meet and affect each other, creating patterns of reinforcement or cancellation.