Other forms: datedly
Something that's dated is very obviously old-fashioned or out of style. Your grandmother's expectation that you send her a written thank-you note whenever she gives you a gift might seem a little dated to you.
Some people can wear thrift shop clothes from the 1980s and look stylish, while others just look dated. And while some movies are still funny even years after they're released, the jokes in others just seem dated. This word meaning "old-fashioned" has been around since the turn of the 20th century, from date, which means both "to mark with a date" and also "to mark as old-fashioned."