ETYM Latin pestis: cf. French peste.
1. An epidemic disease associated with high mortality; specifically; plague.
2. Something resembling a pest in destructiveness; especially; a plant or animal detrimental to humans or human concerns (as agriculture or livestock production).
3. One that pesters or annoys; nuisance.
In biology, any insect, fungus, rodent, or other living organism that has a harmful effect on human beings, other than those that directly cause human diseases. Most pests damage crops or livestock, but the term also covers those that damage buildings, destroy food stores, and spread disease.
A persistently annoying person; SYN. blighter, cuss, pesterer, gadfly.