1. [adj]  out of bed; "are they astir yet?"; "up by seven each morning"
2. [adj]  used up; "time is up"
3. [adj]  (used of computers) operating properly; "how soon will the computers be up?"
4. [adj]  (usually followed by `on' or `for') in readiness; "he was up on his homework"; "had to be up for the game"

UP(P) is a 5 letter word that starts with U.