Let means to allow or permit something to happen. When your teacher lets you go to recess early, she's giving you permission. When you let your friend borrow your book, you're allowing them to take it. The word appears in countless everyday situations: “Mom won't let me stay up late,” or “The referee let the play continue.”

The word often implies a choice not to interfere or stop something. If you let a ball roll past you instead of catching it, you're choosing not to act. When someone says “let it go,” they mean stop worrying about it or leave it alone.

Let can also mean to rent property to someone, though this usage is more common in British English. A landlord might let an apartment to tenants.

In tennis and similar sports, a let is when a point gets replayed, usually because something interfered with fair play. If the ball hits the net but still lands in during a serve, the umpire calls “let” and the server tries again.

The phrase “let alone” means “not to mention” or “much less,” as in “I can't solve this easy problem, let alone the hard one.”