To interpose means to insert something between other things, or to interrupt by placing yourself or your words in the middle of a situation.

When you interpose yourself physically, you're stepping between two people or things. Imagine two friends about to argue on the playground: you might interpose yourself between them, literally standing in the middle to keep them apart and calm things down. A teacher might interpose her hand between a student and a hot stove to prevent a burn.

The word also describes interrupting a conversation to add your thoughts. During a debate between your classmates about which book to read next, you might interpose a comment suggesting a completely different option they hadn't considered. When you interpose a remark, you're inserting your words into the middle of someone else's discussion, ideally in a helpful rather than rude way.

Think of it as positioning something (yourself, an object, or your words) in the space that separates other things. When a lawyer interposes an objection during a trial, she's inserting her protest between the question and the answer.