pestilent
1. [ adjective ] exceedingly harmful
Synonyms: deadly pernicious baneful
Related terms: noxious
2. [ adjective ] likely to spread and cause an epidemic disease
Synonyms: pestilential pestiferous plaguey plaguelike
Examples:

"a pestilential malignancy in the air"- Jonathan Swift "plaguelike diseases" "plaguey fevers"

Related terms: epidemic
Similar spelling:   pestilential
  pestilence
  pestle
  pesthole
  pastille