From un- + trousered.
untrousered (not comparable)
- Not trousered; wearing no trousers.
2007 March 5, Anthony Ramirez, “Threadbare to Quite Posh, in Just 12 Hours”, in New York Times[1]:He liked unwrinkled trousers, so he hung his in a humidor, while he worked untrousered at a desk.