4 syllables:
impossibly

3 syllables:
wallaby, colony, comradely, hostilely, broccoli, modesty, wannabe, rocketry, ology, quantity, novelty, policy, bodily, sodomy, botany, psalmody, homily, prodigy, sovereignty, monstrously, boloney, honesty, twopenny, audibly, frostily, honestly, constantly, quality, ptolemy, hostelry, bonhomie, comedy, dobsonfly, solidly, dovekie, commonly, potbelly, potently, romany, polony, constancy, monody, progeny, wantonly, modestly, consciously, gossipy, colloquy, crotchety, prosody, monandry, cobwebby, odyssey, prophecy, contrasty, probably, wobbly, wannabee, polity, oddity, conakry, balmily, blossomy, bonduc tree, bottletree, caudally, connally, cosily, cozily, dottily, foxily, guenon monkey, knobbly, noxiously, obloquy, promisee, prophesy, rommany, rottenly, squalidly, stodgily, talkily, watchfully

4 syllables:
monopsony, ontogeny, monotony, volubly, autonomy, pomology, cacophony, synonymy, astronomy, psephology, verbosity, technology, sinology, topography, horology, colostomy, conchology, mycology, misogamy, aerology, oncology, demography, geometry, zoology, homogeny, economy, monopoly, ecology, frivolity, garbology, doxology, tocology, neurology, philology, democracy, apostrophe, cytology, lithography, ontology, impolitely, anthology, pornography, comradery, thermometry, geology, geodesy, phonology, phytology, hypocrisy, nosology, demonstrably, orthography, ethnology, penology, gastronomy, atrocity, loquacity, velocity, misology, typography, ichthyology, agrology, trade policy, improbably, viscosity, apostasy, moronity, comparably, proctology, equality, commodity, despondently, inconstancy, porosity, spectroscopy, gibbosity, prodigally, impotency, pathology, philosophy, bureaucracy, planography, dishonesty, photography, theology, neology, virology, conjugally, apology, cartography, monstrosity, jocosity, unconsciously, ethology, serology, psychology, mammography, ethnography, mahogany, insolvency, allopathy, hydrometry, theocracy, phylogeny, tautology, optometry, morphology, agronomy, otology, astrometry, callosity, urology, histology, ferocity, hydrology, geography, mythology, despondency, chronology, posology, anomaly, biology, responsibly, allometry, biography, dichotomy, phrenology, fluoroscopy, low comedy, holography, astrology, enology, idolatry, spectrometry, homology, monogamy, seismology, autocracy, precocity, petrology, limnology, algometry, allotropy, androgeny, apogamy, arthrography, arthroscopy, astrolatry, autogeny, bardolatry, biogeny, cacography, calabash tree, child prodigy, cosmography, cosmolatry, exogamy, farce comedy, globosity, glyptography, gymnosophy, high quality, hydrography, immodestly, immodesty, isogamy, isometry, lithotomy, lordolatry, low quality, mammalogy, monocracy, naprapathy, obnoxiously, old colony, plutocracy, prime quantity, psychometry, pyrolatry, self-consciously, shape constancy, size constancy, sonography, symbolatry, tax policy, tetralogy, theosophy, top-quality, topolatry, tuatha de, venography, verbolatry, viscometry, with modesty, zoolatry

5 syllables:
sinuosity, laparoscopy, hematology, macrocephaly, archeology, anemometry, toxicology, aetiology, cardiography, angiology, actinometry, physiology, eschatology, teratology, rheumatology, anthropology, etymology, child psychology, uranology, true anomaly, dermatology, hagiology, volcanology, mineralogy, bibliography, depth psychology, audiometry, lexicography, haematology, ophthalmology, radiology, axiology, fiscal policy, primatology, inequality, scientology, embryology, adiposity, herpetology, gynaecology, parisology, roentgenography, stereoscopy, tortuosity, etiology, high technology, jejunostomy, crystallography, aristocracy, foreign policy, ideology, tuberosity, egyptology, trigonometry, oenology, mediocrity, teleology, choreography, radiography, methodology, paleology, speleology, ideography, generosity, terminology, audiology, genealogy, cardiology, archaeology, sociology, poenology, animosity, entomology, immunology, criminology, curiosity, ornithology, climatology, adenopathy, irresponsibly, oceanography, anemography, hagiography, tracheostomy, lexicology, meniscectomy, sociometry, pharmacology, plane geometry, gerontology, numerosity, anthropometry, grandiosity, densitometry, anisogamy, gynecology, chromatography, anorthography, angiography, episiotomy, anthropolatry, arborolatry, bibliolatry, brightness constancy, celioscopy, color constancy, complex quantity, constant quantity, defence policy, defense policy, demonolatry, diabolatry, disconsolately, floating policy, glutinosity, greek mythology, gynaeolatry, gyneolatry, hagiolatry, heliolatry, iconolatry, idiolatry, laparotomy, mass spectroscopy, news photography, norse mythology, palaeology, paleography, passamaquody, physiography, preciosity, radioscopy, rail technology, social policy, spelaeology, sumerology, symbololatry, thaumatolatry, tragicomedy, true mahogany, unknown quantity, unselfconsciously, without modesty, xerography

6 syllables:
neuroanatomy, cardiomyopathy, antimonopoly, token economy, psychopathology, market economy, bacteriology, solid geometry, social democracy, autobiography, social psychology, musical comedy, endocrinology, human ecology, chromolithography, paleobotany, ultrasonography, escape velocity, religiosity, geomorphology, folk etymology, neuropsychology, meteorology, biotechnology, cinematography, parapsychology, glottochronology, offset lithography, palaeontology, epistemology, arteriography, neurobiology, insurance policy, paleontology, numismatology, applied psychology, telephotography, microbiology, moral philosophy, muzzle velocity, agrobiology, assyriology, biogeography, cedar mahogany, cholangiography, cholelithotomy, christian theology, compound morphology, cuban mahogany, decline in quality, definite quantity, hypervelocity, legal philosophy, mammothermography, managed economy, maternal quality, mining geology, palaeobotany, palaetiology, paletiology, parental quality, paternal quality, photolithography, powder photography, protozoology, relative quantity, roman mythology, seriocomedy, voluminosity

7 syllables:
projective geometry, natural theology, situation comedy, anesthesiology, psychopharmacology, physical geography, radio astronomy, clinical psychology, paper chromatography, terminal velocity, spherical geometry, african mahogany, paleopathology, epidemiology, bioclimatology, philippine mahogany, cognitive psychology, paleobiology, dynamic viscosity, social anthropology, psychophysiology, dialect geography, electromyography, column chromatography, paleornithology, natural philosophy, neurophysiology, doctor of philosophy, immunopathology, absolute viscosity, animal psychology, classical mythology, clinical neurology, communist economy, computer technology, descriptive geometry, doctor of optometry, doctor of theology, economic policy, genetic psychology, honduras mahogany, indefinite quantity, linguistic geography, marine archaeology, marine archeology, master of theology, numerical quantity, palaeobiology, palaeodendrology, palaeoethnography, palaeogeography, palaeogeology, palaeopathology, palaeornithology, palaeozoology, paleodendrology, paleoethnography, paleogeography, paleogeology, paleomammalogy, paleozoology, parametric quantity, protoanthropology, protoarchaeology, protoarcheology, socialist economy, sociobiology, unit of viscosity, variable quantity

8 syllables:
cultural anthropology, micropaleontology, congenital anomaly, physical anthropology, comparative psychology, economic geography, paleoclimatology, molecular biology, proprietary colony, hyperbolic geometry, industrial psychology, paleoanthropology, analytic geometry, political economy, automotive technology, bachelor of theology, capitalist economy, coordinate geometry, department of biology, department of philosophy, department of psychology, descriptive anthropology, differential psychology, dominican mahogany, economic geology, elementary geometry, empiricist philosophy, human paleontology, large indefinite quantity, national trading policy, palaeoclimatology, parabolic geometry, petroleum geology, small indefinite quantity, transcendental philosophy

9 syllables:
coefficient of viscosity, developmental psychology, experimental psychology, african scented mahogany, analytical geometry, communications technology, department of anthropology, department of sociology, parliamentary democracy, underwater archaeology, underwater archeology

10 syllables:
physiological psychology

11 syllables:
council on environmental policy

12 syllables:
digital communications technology