To permit something means to allow it or give permission for it to happen. When your parents permit you to stay up late on a weekend, they're saying yes to something that normally wouldn't be allowed. When a teacher permits students to work in groups, she's giving them the freedom to collaborate rather than work alone.

The word also works as a noun: a permit is an official document that grants permission to do something specific. A building permit allows someone to construct or renovate a house. A fishing permit gives someone the legal right to fish in certain waters. A parking permit lets you park in spaces that would otherwise be off-limits. Cities issue permits for parades, food trucks, and outdoor events.

Notice the difference between permit and simply let: permit usually sounds more formal and official. You might let your friend borrow your pencil, but a library permits you to check out books. The formality comes from the fact that permitting often involves rules, authority, or legal systems. When weather permits, it means conditions are good enough to allow outdoor activities. When time permits, it means you have enough time available to do something.