Definition of "pest"

pest

/pɛst/

noun
plural pests
1. (now rare) A pestilence, i.e. a deadly epidemic, a deadly plague.
  Quotations
  From the perspective of traditional Chinese culture, pests and famines are reflections of the current administration’s lack of moral values and deviation from divine will. The head of the administration (the emperor in the past) would then issue an edict to sincerely repent and correct his wrongdoings.
  2020 March 24, Qing Zhu, Zhang Ming, “Amid Coronavirus Pandemic, China Faces Plague of Locusts”, in Minghui‎
2. Any destructive insect that attacks crops or livestock; an agricultural pest.
3. An annoying person, a nuisance.
4. An animal regarded as a nuisance, destructive, or a parasite, vermin.
5. An invasive weed.