If your family wakes up early in the morning, you can say they're astir before the sun comes up — or your dog might always be the first one astir each day. You can also use the adjective astir to describe an excited kind of movement: "The whole classroom was astir after the news of tomorrow's pizza party." The earlier phrase was on the stir, from the Old English styrian, "to stir, agitate, or incite."