4 syllables:
subspecialty

2 syllables:
thessaly

3 syllables:
severally, splendidly, pleasantly, messily, hastily, spaciously, tendency, ebony, pedigree, credibly, gemini, venally, leprosy, prelacy, lengthily, elegy, readily, tenantry, weaponry, helplessly, racially, equity, zestfully, remedy, breathlessly, brevity, gratefully, revelry, flexibly, melody, steadily, entity, jealousy, restfully, enemy, seventy, entropy, wastefully, graciously, tensity, vagrancy, peasantry, fatally, clemency, velvety, saliency, threnody, sensibly, devilry, chemistry, pedantry, pregnancy, blatancy, painfully, legacy, aimlessly, bestially, cecity, patiently, necropsy, sesame, zealotry, mentally, density, gracefully, dreadfully, helpfully, shamefully, blatantly, faithlessly, testily, specially, embassy, tenancy, pleasantry, centrally, gracelessly, kennedy, deputy, secondly, enmity, agency, legatee, felony, preciously, blazonry, recipe, faithfully, papacy, ecstasy, especially, debauchee, presently, destiny, heavily, maidenly, atony, heavenly, latency, masonry, medically, endlessly, blamelessly, empathy, crazily, tastefully, jealously, chemically, penalty, vacancy, shamelessly, benghazi, dextrously, ectropy, emigree, evilly, fecklessly, jejunely, legibly, lemony, lenity, melanie, pebbly, pederasty, penally, resiny, self-pity, selflessly, senselessly, sentiency, stephanie, tepidly, trenchancy, trepidly, vengefully, yemeni, zestily, banefully, cadency, cajan pea, capably, gainlessly, heinously, nascency, painlessly, radiancy, sacredly, saleslady, stagily, statesmanly, tastelessly

4 syllables:
press agency, theosophy, outrageously, incessantly, rebelliously, transcendency, contagiously, detestably, acceptably, resplendently, loquaciously, freemasonry, extremity, ascendancy, nonentity, mastectomy, sagaciously, expectancy, identity, necessity, dependably, lamentably, successfully, inequity, discrepancy, sequentially, naivety, unsteadily, lobectomy, ascendency, preferably, complacency, insatiably, disdainfully, tenaciously, serenity, favorably, fidelity, unpleasantly, nephrectomy, potentially, death penalty, tremendously, essentially, flux density, desperately, schenectady, lumpectomy, intrepidly, ostensibly, disgracefully, sententiously, complexity, splenectomy, news agency, insensibly, telemetry, respectfully, respectably, hegemony, generally, inflexibly, dependency, supremacy, salaciously, anemone, longevity, repentantly, ineffably, ungraciously, perplexity, vasectomy, resplendency, solemnity, contemptuously, amenity, federally, belatedly, intensity, impatiently, heredity, perceptibly, convexity, incredibly, integrity, allegedly, courageously, indemnity, incessancy, mistakenly, separately, telepathy, licentiously, low density, regrettably, thrombectomy, tentatively, infectiously, penelope, acephaly, confessedly, defencelessly, domenici, forelady, illegibly, immensity, impendency, impetuously, inclemency, jack kennedy, lieutenancy, neurectomy, perplexedly, polemically, pretentiously, professedly, quiescency, refreshfully, relentlessly, revengefully, shell entity, unhelpfully, vulvectomy, with empathy, adjacency, ad agency, ashamedly, curvaceously, distastefully, dry masonry, flirtatiously, free agency, mendaciously, unchangeably, unfaithfully, ungracefully, ungratefully, unsatiably, unshakably, un agency

5 syllables:
tonsillectomy, orchidectomy, geochemistry, mask of pregnancy, unashamedly, inescapably, hysterectomy, eventually, sympathectomy, life expectancy, sentimentally, ostentatiously, exceptionally, consequentially, confederacy, biochemistry, accidentally, mastoidectomy, independently, tubal pregnancy, reverentially, oophorectomy, white supremacy, professionally, stapedectomy, orchiectomy, pneumonectomy, salpingectomy, thyroidectomy, disrespectfully, appendectomy, penitentially, irreverently, macrencephaly, occasionally, abstemiously, rhytidectomy, incidentally, intemperately, open sesame, providentially, travel agency, high fidelity, prostatectomy, unacceptably, deferentially, unmistakably, photochemistry, independency, conscientiously, embolectomy, microcephaly, fundamentally, vapor density, anencephaly, reprehensibly, unsuccessfully, acrocephaly, change integrity, change intensity, clinocephaly, coalescency, create mentally, detrimentally, drunken revelry, field intensity, half-intensity, high-fidelity, hydrocephaly, intumescency, laminectomy, laryngectomy, line of destiny, macrocephaly, megacephaly, meniscectomy, mortal enemy, mountain ebony, nanocephaly, naval weaponry, of necessity, scaphocephaly, school of dentistry, sigmoidectomy, unforgettably, unpretentiously, unrepentantly, advantageously, causal agency, contumaciously, disputatiously, efficaciously, self-complacency, service agency, unassailably, unattainably

6 syllables:
cholecystectomy, employment agency, unconventionally, coincidentally, biogeography, unintentionally, environmentally, mercantile agency, radiochemistry, physical chemistry, simple mastectomy, impetuosity, manifest destiny, interdependency, electrochemistry, organic chemistry, cercopithecidae, experimentally, inefficaciously, cosmetic dentistry, inconsequentially, adrenalectomy, immunochemistry, relative density, adenoidectomy, anas penelope, appendicectomy, change of integrity, genus penelope, militant tendency, ovariectomy, panhysterectomy, pedal extremity, unsentimentally, cardiomegaly, child welfare agency, commercial agency, detective agency, disadvantageously, government agency

7 syllables:
ovarian pregnancy, radical mastectomy, cyclopean masonry, rotational latency, inorganic chemistry, advertising agency, magnetic flux density, paleogeography, abdominal pregnancy, total hysterectomy, department of chemistry, executive clemency, feeling of identity, john fitzgerald kennedy, magnetic intensity, suprarenalectomy, executive agency

8 syllables:
radical hysterectomy, regulatory agency, conformational entropy, interpersonal chemistry, united nations agency

9 syllables:
central intelligence agency

10 syllables:
modified radical mastectomy

11 syllables:
environmental protection agency

14 syllables:
international atomic energy agency