The word used has several meanings:

1. Something that has been owned or utilized before by someone else. A used car has had previous owners, while a used book shows signs that others have read it, like creased pages or highlighted passages. Used items cost less than new ones because they've already served someone else, though many work just as well. Libraries sell used books to make room for new ones, and some families save money by buying used clothing or furniture.
2. The past tense of the verb “use,” meaning to employ something for a purpose. Yesterday you used a calculator to solve math problems. Your grandmother used a typewriter before computers existed. When something has been used up, nothing remains: you used all the paper in the printer, or you used the last egg to make pancakes.
3. To describe a former habit or regular state, as in “used to.” This shows something that was once true but isn't anymore. You might say “I used to be afraid of dogs” if you've overcome that fear, or “She used to live in Texas” if she's since moved away. This meaning captures how people and situations can change over time.