Other forms: outdatedly
Anything that's so old-fashioned that it's unstylish or not useful is outdated. You might love the way an antique car looks, but its outdated safety standards (no seat belts or airbags) make it dangerous to drive on the highway.
The 70s bell-bottom jeans your aunt still wears might be embarrassingly outdated, but at least they function as pants. Your outdated computer, on the other hand, isn't even capable of getting online or connecting to your printer — in other words, it's obsolete, or completely useless. This adjective dates from the early 1600s, from the "mark as old fashioned" meaning of the verb date.