outmoded

Something that is outmoded is no longer cool or in style, like your dad's outmoded hairstyle that he's had since he was in high school.

The French are known for their sense of fashion and style, so it's no surprise that they coined the word démodé to describe things that are no longer cool. De- means "out, off, away" and mode means "fashion." The English word outmoded is simply a translation of démodé: "out of fashion" or "out of style."