Meaning

noun a serious (sometimes fatal) infection of rodents caused by Yersinia pestis and accidentally transmitted to humans by the bite of a flea that has bitten an infected animal

noun any epidemic disease with a high death rate

noun a persistently annoying person

originIn the 16th century in the sense of "pestilence" and specifically bubonic plague from Middle French peste (“pestilence”) (whence French peste). The other meanings are recorded soon after. Ultimately from Latin pestis.

Etymology from Wiktionary, CC BY-SA 3.0