2 syllables:
vileness

3 syllables:
blissfulness, impetus, sinfulness, impotence, 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, cliquishness, fisticuffs, fittingness, impishness, indigence, litigious, mytilus, piggishness, priggishness, rypticus, sickeningness, skittishness, timidness, willingness

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, certificates, coincidence, commitedness, convincingness, distinctiveness, duplicitous, forgivingness, long-windedness, permissiveness, precipitous, quick-wittedness, restrictiveness, significance, slow-wittedness, submissiveness, tightfistedness, ubiquitous, umbilicus, vindictiveness

5 syllables:
telekinesis, meretriciousness, indefiniteness, canaliculus, diakinesis, chemosynthesis, irreligiousness, inauspiciousness, geosynchronous, infelicitous, aspergillosis, unambiguous, insignificance, unpermissiveness

6 syllables:
angle of incidence, australopithecus, conditioned stimulus