AWOL means you are not where you are supposed to be, and nobody gave you permission to go. It began in the United States army as a short way to say “absent without official leave.” A soldier who is AWOL has left their post or camp without the papers that say they may. In that world it is serious — a military offence — though actually it is not always the same as desertion, which is leaving and not meaning to come back. Outside the army, people borrowed it. A classmate who vanishes from a group project, a drummer who does not show, a friend who promised to come to dinner and then disappeared: people say they went AWOL. That looser use is informal, a bit jokey, and it still carries “missing without a good excuse.” You can use it as an adjective (He is AWOL) or as a noun in the set phrase go AWOL. Most people say the letters, A-W-O-L; some say it as one word, like “AY-wol.”