pestilent

/ˈpɛstələnt/
adjective
  1. Causing or likely to cause a deadly infectious disease; plague-like.
    • Medieval doctors wore masks to protect themselves from pestilent air.
    • The swamp was considered a pestilent place, full of fever-carrying mosquitoes.
    • The pestilent rats spread disease through the crowded city.
  2. Annoying or harmful in a persistent way; troublesome.
    • She found the constant spam emails to be a pestilent nuisance.
    • The pestilent noise from the construction site made it impossible to concentrate.
    • My little brother has a pestilent habit of leaving his toys all over the floor.
Antonyms
What does "pestilent" mean? | whatsthatwordmean | whatsthatwordmean