To drop off means to take someone or something to a place and leave them there. Every morning, parents might drop off their children at school before heading to work. You might drop off a library book in the return slot, or drop off a package at the post office.

The phrase suggests a quick stop rather than staying: you arrive, leave what you brought, and continue on your way. When you drop someone off, you're giving them a ride to their destination but not going inside with them. A carpool parent might drop off three kids at soccer practice, waving goodbye as they pile out of the car.

The word also describes something that falls away or decreases sharply. If a hiking trail has a steep drop-off on one side, it means the ground suddenly falls away into a cliff or ravine. When scientists say interest in a topic has dropped off, they mean it declined quickly. You might notice that your energy drops off in the afternoon, or that attendance at a club meeting dropped off after the first few weeks of school.

As a noun, a drop-off can mean the place where you leave things or people. Many schools have a specific drop-off zone where cars line up in the morning.