The Collaborative International Dictionary of English v.0.48:

Pest \Pest\, n. [L. pestis: cf. F. peste.]
   1. A fatal epidemic disease; a pestilence; specif., the
      plague.
      [1913 Webster]

            England's sufferings by that scourge, the pest.
                                                  --Cowper.
      [1913 Webster]

   2. Anything which resembles a pest; one who, or that which,
      is troublesome, noxious, mischievous, or destructive; a
      nuisance. "A pest and public enemy." --South.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pest
    n 1: 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 [syn:
         plague, pestilence, pest, pestis]
    2: any epidemic disease with a high death rate [syn: plague,
       pestilence, pest]
    3: a persistently annoying person [syn: pest, blighter,
       cuss, pesterer, gadfly]
    4: any unwanted and destructive insect or other animal that
       attacks food or crops or livestock etc.; "he sprayed the
       garden to get rid of pests"; "many pests have developed
       resistance to the common pesticides"

Moby Thesaurus II by Grady Ward, 1.0:

122 Moby Thesaurus words for "pest":
   affliction, aggravation, ambulatory plague, annoyance, annoyer,
   bad news, badgerer, bane, bedevilment, besetment, black death,
   black plague, blast, blight, bore, bother, botheration,
   bothersomeness, bubonic plague, bugbear, bully, burden,
   buttonholer, calamity, cancer, canker, cellulocutaneous plague,
   crashing bore, crushing burden, curse, death, defervescing plague,
   destruction, devilment, difficulty, disease, dogging, downer, drag,
   drip, dry rot, dryasdust, dusty, epidemic, epiphytotic, epizootic,
   evil, exasperation, flat tire, frightful bore, fungus, gadfly,
   glandular plague, grievance, harasser, harassment, harm, harrier,
   harrying, headache, heckler, hemorrhagic plague, hounding, humdrum,
   infliction, irritant, larval plague, mildew, mold, molestation,
   moth, moth and rust, murrain, must, nag, nemesis, nudnik, nudzh,
   nuisance, open wound, pandemia, pandemic, persecution, persecutor,
   pester, pesterer, pesthole, pestilence, pill, plague, plague spot,
   plaguer, pneumonic plague, premonitory plague, problem, proser,
   rot, running sore, rust, sadist, scourge, septicemic plague,
   siderating plague, smut, tease, teaser, thorn, torment, tormentor,
   trial, trouble, tuberculosis, twaddler, vexation, vexatiousness,
   visitation, wet blanket, white plague, woe, worm, worriment,
   worry



V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

PEST
       Parameter Estimation by Sequential Testing