1. [adj]  lacking embellishment or ornamentation; "a plain hair style"; "unembellished white walls"; "functional architecture featuring stark unornamented concrete"
2. [adj]  lacking stylistic embellishment; "a literal description"; "wrote good but plain prose"; "a plain unadorned account of the coronation"; "a forthright unembellished style"

UNEMBELLISHED is a 13 letter word that starts with U.