5 letters:
otomy

7 letters:
axotomy, myotomy, ototomy, peotomy, scotomy, zootomy

8 letters:
aplotomy, celotomy, colotomy, ileotomy, kelotomy, labotomy, menotomy, oncotomy, onkotomy, tenotomy, vagotomy, venotomy, xylotomy

9 letters:
adenotomy, androtomy, aortotomy, celiotomy, cirsotomy, colpotomy, coniotomy, cordotomy, costotomy, cricotomy, culdotomy, cyclotomy, cystotomy, dichotomy, frenotomy, goniotomy, hippotomy, histotomy, iridotomy, leucotomy, leukotomy, lithotomy, mammotomy, mastotomy, meatotomy, necrotomy, neurotomy, orchotomy, orthotomy, phytotomy, pubiotomy, pulpotomy, rhinotomy, tarsotomy, tendotomy, thyrotomy, uterotomy, valvotomy

10 letters:
angeiotomy, arthrotomy, atticotomy, blastotomy, canthotomy, cardiotomy, chordotomy, craniotomy, dichotomie, embryotomy, enterotomy, entomotomy, episiotomy, fasciotomy, glossotomy, hepatotomy, herniotomy, hymenotomy, jejunotomy, keratotomy, laminotomy, laparotomy, nephrotomy, onychotomy, orbitotomy, ovariotomy, pelviotomy, phlebotomy, plasmotomy, pleurotomy, pneumotomy, pogonotomy, proctotomy, pylorotomy, rachiotomy, radicotomy, rumenotomy, sclerotomy, sinusotomy, splenotomy, sternotomy, strabotomy, tractotomy, vaginotomy, varicotomy, ventrotomy, vesicotomy

11 letters:
achillotomy, adhesiotomy, alveolotomy, arteriotomy, bronchotomy, callosotomy, capsulotomy, cephalotomy, chondrotomy, cingulotomy, condylotomy, duodenotomy, escharotomy, fistulotomy, herpetotomy, hippopotami, hysterotomy, ichthyotomy, lacrimotomy, laryngotomy, myotenotomy, myringotomy, omphalotomy, orchidotomy, ornithotomy, pallidotomy, perineotomy, polychotomy, syringotomy, thalamotomy, thoracotomy, tonsilotomy, tracheotomy, ureterotomy, urethrotomy, valvulotomy

12 letters:
amygdalotomy, anthropotomy, aponeurotomy, blepharotomy, esophagotomy, foraminotomy, ossiculotomy, pharyngotomy, pneumonotomy, prostatotomy, salpingotomy, sigmoidotomy, staphylotomy, subdichotomy, syndesmotomy, thyroidotomy, tonsillotomy, trachelotomy

13 letters:
encephalotomy, pancreatotomy, pottawattomie, pyloromyotomy, splanchnotomy, stricturotomy, symphyseotomy, symphysiotomy, vestibulotomy

14 letters:
cholecystotomy, choledochotomy, cholelithotomy, commissurotomy, cricothyrotomy, cystolithotomy, lymphangiotomy, mediastinotomy, minilaparotomy, pericardiotomy, pyelolithotomy, sphincterotomy, synchondrotomy, ultramicrotomy, ventriculotomy

15 letters:
achillotenotomy, dacryocystotomy, nephrolithotomy

16 letters:
gastroelytrotomy

17 letters:
cricothyroidotomy, gastrohysterotomy

18 letters:
laryngotracheotomy

19 letters:
abdominohysterotomy, choledocholithotomy

5 letters:
ology

6 letters:
nobody, openly, cozily, bosomy, romany, bodily, botany, colony, comedy, cosily, foxily, homily, monody, oddity, policy, polity, sodomy, wobbly

7 letters:
exogamy, cogency, locally, ojibway, probity, potency, totally, notably, anomaly, apogamy, apology, audibly, balmily, biogeny, biology, conakry, dottily, ecology, economy, enology, geodesy, geology, gossipy, honesty, isogamy, knobbly, modesty, neology, novelty, obloquy, odyssey, otology, prodigy, progeny, prosody, ptolemy, quality, rommany, solidly, talkily, urology, wallaby, wannabe, zoology

8 letters:
endogamy, woefully, yeomanry, socially, podiatry, momently, sociably, allogamy, globally, aerology, agrology, agronomy, atrocity, autogeny, autonomy, axiology, blossomy, bonhomie, broccoli, caudally, colloquy, commonly, connally, cytology, doxology, equality, ethology, etiology, ferocity, geometry, homogeny, homology, honestly, horology, hostelry, ideology, idolatry, isometry, mahogany, modestly, monogamy, monopoly, monotony, mycology, nosology, oenology, oncology, ontogeny, ontology, penology, pomology, porosity, possibly, probably, promisee, prophecy, prophesy, psalmody, quantity, rocketry, rottenly, serology, sinology, stodgily, theology, tocology, velocity, virology, wannabee, wantonly, zoolatry

9 letters:
diplomacy, dolefully, hopefully, copiously, aetiology, algometry, allometry, allotropy, androgeny, angiology, animosity, anthology, astrology, astronomy, audiology, autocracy, biography, cacophony, callosity, commodity, constancy, crotchety, curiosity, democracy, ethnology, etymology, frivolity, genealogy, geography, globosity, hagiology, histology, hostilely, hydrology, hypocrisy, idiolatry, immodesty, limnology, mammalogy, monocracy, monopsony, mythology, neurology, noxiously, optometry, paleology, pathology, petrology, philology, phonology, phylogeny, phytology, poenology, precocity, pyrolatry, radiology, sociology, squalidly, tautology, tetralogy, theocracy, theosophy, topolatry, tuatha de, uranology, verbosity, viscosity

10 letters:
boastfully, hopelessly, supposedly, astrolatry, anemometry, apostrophe, archeology, astrometry, audiometry, bardolatry, bottletree, cacography, cardiology, celioscopy, chronology, comparably, conchology, constantly, cosmolatry, demography, diabolatry, dishonesty, egyptology, embryology, entomology, gastronomy, generosity, gymnosophy, gynecology, gyneolatry, hagiolatry, heliolatry, hematology, hydrometry, iconolatry, ideography, immodestly, immunology, impossibly, improbably, inequality, insolvency, lexicology, lordolatry, low comedy, mediocrity, mineralogy, morphology, naprapathy, numerosity, old colony, palaeology, philosophy, phrenology, physiology, plutocracy, preciosity, proctology, psephology, psychology, radioscopy, seismology, sociometry, sonography, speleology, sumerology, symbolatry, tax policy, technology, topography, toxicology, tuberosity, typography, venography, verbolatry, viscometry, watchfully, xerography

11 letters:
psychometry, atrociously, acrocephaly, procyonidae, emotionally, agrobiology, anemography, arborolatry, archaeology, aristocracy, arthroscopy, assyriology, bibliolatry, bonduc tree, bureaucracy, cartography, climatology, consciously, cosmography, criminology, demonolatry, dermatology, despondency, eschatology, ethnography, fluoroscopy, gerontology, glutinosity, grandiosity, gynaecology, gynaeolatry, haematology, hagiography, hydrography, inconstancy, laparoscopy, lithography, low quality, mammography, meteorology, methodology, monstrosity, monstrously, obnoxiously, ornithology, orthography, paleobotany, paleography, paletiology, photography, planography, pornography, primatology, radiography, religiosity, responsibly, scientology, seriocomedy, sovereignty, spelaeology, terminology, thermometry, top-quality, tragicomedy

12 letters:
anthropogeny, anthropology, antimonopoly, arthrography, bacteriology, bibliography, biogeography, cardiography, choreography, demonstrably, densitometry, despondently, epidemiology, epistemology, farce comedy, glyptography, high quality, lexicography, microbiology, neurobiology, oceanography, palaeobotany, palaetiology, paleobiology, paleogeology, paleontology, paleozoology, passamaquody, pharmacology, physiography, protozoology, rheumatology, sociobiology, spectrometry, spectroscopy, symbololatry, trade policy, trigonometry, true anomaly, voluminosity, with modesty

13 letters:
reproachfully, ceremoniously, anorthography, anthropolatry, anthropometry, arteriography, autobiography, biotechnology, calabash tree, child prodigy, endocrinology, fiscal policy, geomorphology, guenon monkey, human ecology, hypervelocity, irresponsibly, numismatology, ophthalmology, palaeobiology, palaeogeology, palaeontology, palaeozoology, social policy, thaumatolatry, token economy, true mahogany, unconsciously

14 letters:
anesthesiology, bioclimatology, cedar mahogany, chromatography, cinematography, cuban mahogany, defence policy, defense policy, disconsolately, folk etymology, foreign policy, market economy, mining geology, musical comedy, paleogeography, paleomammalogy, paleopathology, parapsychology, plane geometry, prime quantity, size constancy, solid geometry

15 letters:
cholangiography, color constancy, crystallography, economic policy, escape velocity, floating policy, greek mythology, high technology, immunopathology, managed economy, muzzle velocity, neurophysiology, neuropsychology, norse mythology, palaeogeography, palaeopathology, paleodendrology, paleornithology, protoarcheology, psychopathology, radio astronomy, rail technology, roentgenography, roman mythology, shape constancy, telephotography, ultrasonography, without modesty

16 letters:
dollar diplomacy, african mahogany, child psychology, complex quantity, depth psychology, economic geology, electromyography, glottochronology, insurance policy, legal philosophy, maternal quality, moral philosophy, natural theology, news photography, palaeodendrology, palaeornithology, paleoclimatology, paleoethnography, parental quality, paternal quality, photolithography, protoarchaeology, psychophysiology, self-consciously, situation comedy, social democracy, unknown quantity

17 letters:
gunboat diplomacy, analytic geometry, animal psychology, chromolithography, communist economy, constant quantity, definite quantity, dialect geography, dynamic viscosity, honduras mahogany, mammothermography, marine archeology, mass spectroscopy, micropaleontology, molecular biology, palaeoclimatology, palaeoethnography, paleoanthropology, petroleum geology, political economy, protoanthropology, relative quantity, socialist economy, social psychology, terminal velocity, unit of viscosity, unselfconsciously, variable quantity

18 letters:
absolute viscosity, applied psychology, capitalist economy, christian theology, clinical neurology, congenital anomaly, decline in quality, doctor of theology, dominican mahogany, economic geography, genetic psychology, human paleontology, marine archaeology, master of theology, natural philosophy, numerical quantity, offset lithography, parabolic geometry, physical geography, powder photography, proprietary colony, psychopharmacology, spherical geometry

19 letters:
analytical geometry, classical mythology, clinical psychology, compound morphology, computer technology, coordinate geometry, doctor of optometry, elementary geometry, hyperbolic geometry, indefinite quantity, parametric quantity, philippine mahogany, projective geometry, social anthropology

20 letters:
bachelor of theology, brightness constancy, cognitive psychology, descriptive geometry, doctor of philosophy, linguistic geography, paper chromatography

21 letters:
automotive technology, column chromatography, cultural anthropology, department of biology, empiricist philosophy, industrial psychology, physical anthropology, underwater archeology

22 letters:
comparative psychology, underwater archaeology

23 letters:
department of sociology, differential psychology, experimental psychology, national trading policy, parliamentary democracy

24 letters:
african scented mahogany, coefficient of viscosity, department of philosophy, department of psychology, descriptive anthropology, developmental psychology, physiological psychology

25 letters:
communications technology, large indefinite quantity, small indefinite quantity, transcendental philosophy

26 letters:
department of anthropology

31 letters:
council on environmental policy

33 letters:
digital communications technology