3 syllables:
mimulus, stimulus

6 syllables:
aversive stimulus, conditioned stimulus, negative stimulus, positive stimulus

7 syllables:
reinforcing stimulus

10 syllables:
negative reinforcing stimulus, positive reinforcing stimulus

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, immanence, diclinous, diffidence, limitless, frivolous, mischievous, singultus, spitefulness, mindlessness, skillfulness, instruments, simpleness, vividness, villainous, alikeness, wistfulness, brittleness, 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, deliciousness, officiousness, ridiculous, religiousness, antithesis, precipitance, equivalence, saint nicholas, asynchronous, maliciousness, leviticus, capriciousness, cuniculus, bicephalous, omnipotence, pediculus, perniciousness, felicitous, ambivalence, acidulous, utriculus, iniquitous, propitiousness, suspiciousness, nonsynchronous, declivitous, funiculus, auspiciousness, ambitiousness, acclivitous, ambitionless, antigonus, assiduousness, erithacus, explicitness, grandiloquence, illicitness, implicitness, insipidness, judiciousness, magnificence, magniloquence, munificence, nutritiousness, participants, unchivalrous, unmindfulness, unskillfulness, ventriculus

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

6 syllables:
angle of incidence, australopithecus, aegyptopithecus, algeripithecus, relative incidence

7 syllables:
ouranopithecus

8 syllables:
genus australopithecus