Drain means to remove liquid from something, letting it flow away until nothing's left. When you drain pasta, you pour off the cooking water through a colander. When a plumber drains a water heater, they empty it completely for repairs. After a heavy rain, storm drains help water flow off streets and into underground pipes.

The word also describes what happens when something gradually empties or loses its contents. A phone battery drains when you use too many apps without charging it. Energy drains from your body after running hard at recess. A long, difficult math problem might drain your mental energy, leaving you feeling tired and spent.

Something that constantly takes your time, energy, or resources without giving much back is called a drain. If your little brother keeps interrupting while you're trying to read, he's being a drain on your patience. If a leaky faucet wastes water all night, that's a drain on your family's water bill.

As a noun, a drain is also the opening where water flows away, like the drain in a bathtub or sink. When something goes down the drain, it's lost or wasted, like when you accidentally drop your eraser down the sink drain or when poor planning sends a group project down the drain.