Something that's out-of-date is either old-fashioned or so old that it's invalid. An expired driver's license is out-of-date, and the out-of-date milk in your refrigerator is pretty likely to smell sour. Another way to be out-of-date is to be hopelessly unfashionable, like grandparents' out-of-date kitchen, with its appliances from 1970. You can also use the words obsolete or outdated as synonyms for out-of-date, for most things.