1.  pestilence(n = noun.state) pest, pestis, plague - 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;
is a kind of epidemic disease
has particulars: bubonic plague, glandular plague, pestis bubonica, plague pneumonia, pneumonic plague, pulmonic plague, septicemic plague

2.  pestilence(n = noun.state) pest, plague - any epidemic disease with a high death rate;
is a kind of epidemic disease
Derived forms adjective pestilent₂, adjective pestilential₁

3.  pestilence(n = noun.cognition) canker - a pernicious and malign influence that is hard to get rid of; "racism is a pestilence at the heart of the nation"; "according to him, I was the canker in their midst"
is a kind of influence
Derived form adjective pestilent₁

1.  Specifically, the disease known as the plague; hence, any contagious or infectious epidemic disease that is virulent and devastating. [1913 Webster]
"The pestilence That walketh in darkness." [1913 Webster]

2.  Fig.: That which is pestilent, noxious, or pernicious to the moral character of great numbers. [1913 Webster]
"I'll pour this pestilence into his ear." [1913 Webster]

pestilence, n. a fatal epidemic disease, esp. bubonic plague.

Etymology:
ME f. OF f. L pestilentia (as PESTILENT)

N  badness, hurtfulness, virulence, evil doer, bane, plague spot, evil star, ill wind, hoodoo, Jonah, snake in the grass, skeleton in the closet, amari aliquid, thorn in the side, malignity, malevolence, tender mercies, ill-treatment, annoyance, molestation, abuse, oppression, persecution, outrage, misusage, injury, knockout drops, badness, peccancy, abomination, painfulness, pestilence, guilt, depravity, hurtful, harmful, scathful, baneful, baleful, injurious, deleterious, detrimental, noxious, pernicious, mischievous, full of mischief, mischief-making, malefic, malignant, nocuous, noisome, prejudicial, disserviceable, disadvantageous, wide-wasting, unlucky, sinister, obnoxious, untoward, disastrous, oppressive, burdensome, onerous, malign, corrupting &c (corrupt), virulent, venomous, envenomed, corrosive, poisonous, deadly, destructive, inauspicious, bad, ill, arrant, as bad as bad can be, dreadful, horrid, horrible, dire, rank, peccant, foul, fulsome, rotten, rotten at the core, vile, base, villainous, mean, injured, deteriorated, unsatisfactory, exceptionable indifferent, below par, illcontrived, ill-conditioned, wretched, sad, grievous, deplorable, lamentable, pitiful, pitiable, woeful, evil, wrong, depraved, shocking, reprehensible, hateful, hateful as a toad, abominable, detestable, execrable, cursed, accursed, confounded, damned, damnable, infernal, diabolic, unadvisable, unprofitable, incompetent, irremediable, badly, wrong, ill, to one's cost, where the shoe pinches, bad is the best: the worst come to the worst, herba mala presto cresco, wrongs unredressed or insults unavenged.

N  disease, illness, sickness, ailing, all the ills that flesh is heir to, morbidity, morbosity, infirmity, ailment, indisposition, complaint, disorder, malady, distemper, distemperature, visitation, attack, seizure, stroke, fit, delicacy, loss of health, invalidation, cachexy, cachexia, atrophy, marasmus, indigestion, dyspepsia, decay, decline, consumption, palsy, paralysis, prostration, taint, pollution, infection, sepsis, septicity, infestation, epidemic, pandemic, endemic, epizootic, murrain, plague, pestilence, pox, sore, ulcer, abscess, fester, boil, pimple, wen, carbuncle, gathering, imposthume, peccant humor, issue, rot, canker, cold sore, fever sore, cancer, carcinoma, leukemia, neoplastic disease, malignancy, tumor, caries, mortification, corruption, gangrene, sphacelus, sphacelation, leprosy, eruption, rash, breaking out, fever, temperature, calenture, inflammation, ague, angina pectoris, appendicitis, Asiatic cholera, spasmodic cholera, biliary calculus, kidney stone, black death, bubonic plague, pneumonic plague, blennorrhagia, blennorrhoea, blood poisoning, bloodstroke, bloody flux, brash, breakbone fever, dengue fever, malarial fever, Q-fever, heart attack, cardiac arrest, cardiomyopathy, hardening of the arteries, arteriosclerosis, atherosclerosis, bronchocele, canker rash, cardialgia, carditis, endocarditis, cholera, asphyxia, chlorosis, chorea, cynanche, dartre, enanthem, enanthema, erysipelas, exanthem, exanthema, gallstone, goiter, gonorrhea, green sickness, grip, grippe, influenza, flu, hay fever, heartburn, heaves, rupture, hernia, hemorrhoids, piles, herpes, itch, king's evil, lockjaw, measles, mumps, polio, necrosis, pertussis, phthisis, pneumonia, psora, pyaemia, pyrosis, quinsy, rachitis, ringworm, rubeola, St. Vitus's dance, scabies, scarlatina, scarlet fever, scrofula, seasickness, struma, syntexis, tetanus, tetter, tonsillitis, tonsilitis, tracheocele, trachoma, trismus, varicella, varicosis, variola, water qualm, whooping cough, yellow fever, yellow jack, fatal disease, dangerous illness, galloping consumption, churchyard cough, general breaking up, break up of the system, idiocy insanity, martyr to disease, cripple, the halt the lame and the blind, valetudinary, valetudinarian, invalid, patient, case, sickroom, sick- chamber, pathology, etiology, nosology, anthrax, bighead, blackleg, blackquarter, cattle plague, glanders, mange, scrapie, milk sickness, heartworm, feline leukemia, roundworms, quarter-evil, quarter-ill, rinderpest, virus, bacterium, bacteria, DNA virus, RNA virus, rhinovirus, rhabdovirus, picornavirus, herpesvirus, cytomegalovirus, CMV, human immunodefficiency virus, HIV, diseased, ailing, ill, ill of, taken ill, seized with, indisposed, unwell, sick, squeamish, poorly, seedy, affected with illness, afflicted with illness, laid up, confined, bedridden, invalided, in hospital, on the sick list, out of health, out of sorts, under the weather, valetudinary, unsound, unhealthy, sickly, morbid, morbose, healthless, infirm, chlorotic, unbraced, drooping, flagging, lame, crippled, halting, morbid, tainted, vitiated, peccant, contaminated, poisoned, tabid, mangy, leprous, cankered, rotten, rotten to the core, rotten at the core, withered, palsied, paralytic, dyspeptic, luetic, pneumonic, pulmonic, phthisic, rachitic, syntectic, syntectical, tabetic, varicose, touched in the wind, broken-winded, spavined, gasping, hors de combat, weakly, weakened, decrepit, decayed, incurable, in declining health, cranky, in a bad way, in danger, prostrate, moribund, morbific epidemic, endemic, zymotic.