A loaner is something you borrow temporarily while your own item is being fixed or replaced. When your family's car needs repairs, the mechanic might give you a loaner car to drive until yours is ready. If your laptop breaks and needs to be sent away for a week, the school might provide a loaner laptop so you can keep up with your work.

The key idea is that a loaner fills in during a gap. It's not a gift and it's not permanently yours: you're expected to return it once you get your original item back. Libraries offer loaner laptops and tablets. Some stores provide loaner equipment while they repair what you brought in.

A loaner isn't usually as nice or personalized as what you normally use (it won't have your favorite stickers or settings), but it keeps you going until the real thing is back. Teachers sometimes keep loaner pencils at their desks for students who forget theirs. The understanding is simple: you use it for now, you take care of it, and you give it back when you're done.