Lewis & Short

dē-dĕcŏrōsus, a, um, adj., disgraceful, dishonorable (post-Aug., and very rare): nex, Aur. Vict. Epit. 39 fin.
Comp.,
Hier. in Jes. 16, 58, 10.
Adv.: dēdĕcŏ-rōse, disgracefully: vixi, turpius peream, Nero ap. Aur. Vict. Epit. 5 fin.