1. [adj]  lacking a caretaker; "a neglected child"; "many casualties were lying unattended"
2. [adj]  lacking accompaniment or a guard or escort; "unattended women"; "problems unattended with danger"
3. [adj]  not watched; "she dashed out leaving the bar unattended"; "a fire left unattended"

UNATTENDED is a 10 letter word that starts with U.