An olive is a very small fruit, although you probably think of it as a savory snack. You might find an olive on a salad, on a pizza, or even on a toothpick in your martini.
Olives are so naturally bitter that they're basically inedible unless they've been treated — cured with lye or salt, and then fermented. In addition to the olives you see in jars on grocery store shelves, olive trees yield an expensive, durable wood; and of course, olive oil. You can also describe the yellowish-green color of an unripe olive as olive. And when someone offers "an olive branch," they are trying to make peace or come to an understanding.