Pestilential
Pronunciation : Pes`ti*len"tial
Part of Speech : a.
Etymology : [Cf. F. pestilentiel.]
Definition : 1. Having the nature or qualities of a pestilence. "Sends the pestilential vapors." Longfellow.
2. Hence: Mischievous; noxious; pernicious; morally destructive. So pestilential, so infectious a thing is sin. Jer. Taylor.
Source : Webster's Unabridged Dictionary, 1913