3 syllables:
viciousness, vitiousness

4 syllables:
ambitiousness, auspiciousness, capriciousness, deliciousness, factitiousness, fictitiousness, flagitiousness, judiciousness, lubriciousness, maliciousness, nutritiousness, perniciousness, propitiousness, seditiousness, suspiciousness

5 syllables:
adventitiousness, expeditiousness, inauspiciousness, injudiciousness, meretriciousness, repetitiousness, superstitiousness, surreptitiousness, unambitiousness, unpropitiousness

2 syllables:
vileness

3 syllables:
impetus, sinfulness, impotence, blissfulness, willfulness, imminence, synchronous, pythoness, vigilance, innocence, winsomeness, fistulous, minuteness, wickedness, nicholas, ninepence, bibulous, singleness, nimbleness, listlessness, synthesis, littleness, insolence, diligence, fickleness, ricinus, syllabus, dissonance, dictamnus, incidence, stimulus, immanence, diclinous, diffidence, limitless, frivolous, mischievous, singultus, spitefulness, mindlessness, skillfulness, instruments, simpleness, vividness, villainous, alikeness, wistfulness, brittleness, limulus, infamous, chivalrous, citrullus, dissidents, fitfulness, fixedness, gibbousness, givenness, guiltlessness, immigrants, incidents, indolence, innocense, innocents, linanthus, lissomeness, militance, militants, nimravus, quiscalus, risklessness, shiftlessness, siliceous, sinlessness, sinuousness, symptomless, synthesise, thriftlessness, tinnitus, villainess, viscidness, viscousness, wilfulness, windlessness, wishfulness, wrinkleless

4 syllables:
infiniteness, calyculus, vertiginous, polygamous, indigenous, meticulous, ridiculous, religiousness, antithesis, precipitance, equivalence, saint nicholas, asynchronous, leviticus, cuniculus, bicephalous, omnipotence, pediculus, felicitous, ambivalence, acidulous, utriculus, iniquitous, nonsynchronous, declivitous, funiculus, acclivitous, ambitionless, antigonus, assiduousness, erithacus, explicitness, grandiloquence, illicitness, implicitness, insipidness, magnificence, magniloquence, munificence, participants, unchivalrous, unmindfulness, unskillfulness, ventriculus

5 syllables:
telekinesis, indefiniteness, canaliculus, diakinesis, chemosynthesis, irreligiousness, geosynchronous, infelicitous, aspergillosis, unambiguous, biosynthesis, cercopithecus, dryopithecus, inexplicitness, kenyapithecus, lufengpithecus, mental synthesis, nonequivalence, rudapithecus, sivapithecus

6 syllables:
angle of incidence, australopithecus, conditioned stimulus, aegyptopithecus, algeripithecus, aversive stimulus, negative stimulus, positive stimulus, relative incidence

7 syllables:
ouranopithecus, reinforcing stimulus

8 syllables:
genus australopithecus

10 syllables:
negative reinforcing stimulus, positive reinforcing stimulus