Someone dowdy dresses badly and has a shabby, unstylish appearance. If you can’t remember the last time you went shopping, beware, you may be dowdy.
People tend to use the word dowdy mostly to describe women, in particular older women. In addition, it not only means shabbily dressed, but also relates specifically to the idea of style, or rather the lack of it. Applied to clothing, it also means out of date, in an old-fashioned, dull sort of way. Wild 1970s-style love beads may be out of style, but they can never be called dowdy! A sensible gray tweed skirt or the person wearing it? Most likely dowdy!