To obligate means to require someone to do something or to make them responsible for it. When you sign up for a sports team, you obligate yourself to attend practices and games. When a law obligates stores to check IDs before selling certain items, it makes checking IDs a requirement, not a choice.

Being obligated is different from volunteering: if you're obligated to help clean up after a party, you must do it, whether you feel like it or not. Maybe you promised the host, or maybe your parents told you it's your responsibility. Either way, you can't just skip it.

The word comes from legal and formal agreements. When a company signs a contract, it obligates the company to fulfill specific terms. When you borrow a library book, you're obligated to return it on time. An obligation is the duty or requirement itself: returning that library book is your obligation.

Sometimes people feel obligated even when no one explicitly told them they had to do something. You might feel obligated to invite a classmate to your party because they invited you to theirs, or obligated to help a neighbor who once helped you. These social obligations aren't written down anywhere, but they still feel like real responsibilities.