3 syllables:
pederasty, airily, barony, cheerily, cherokee, clarity, clerisy, curacy, currency, currently, dorothy, drearily, eerily, errancy, fierily, forestry, heraldry, heresy, heronry, horribly, horridly, irony, jeremy, laurel-tree, merrily, morally, neuralgy, orally, parity, parody, piracy, pleurisy, purity, rarity, scarily, surety, syrupy, terribly, therapy, touristry, touristy, tyranni, tyranny, verity, warily, warranty, wearily

4 syllables:
reverently, desperately, dexterously, preferably, generously, federally, severalty, pleasurably, memorably, temperately, generally, separately, measurably, aberrancy, adorably, apparency, apparently, authority, barbarity, binaurally, celerity, coherency, coherently, concurrently, conspiracy, contrarily, deplorably, dexterity, disparity, hilarity, immorally, impurity, inerrancy, inherently, legerity, majority, maturity, minority, molarity, monaurally, obscurity, polarity, posterity, primarily, priority, prosperity, security, shock therapy, sincerity, sonority, sorority, speech therapy, temerity, transparency, unwarily

5 syllables:
inseparably, confederacy, degeneracy, peremptorily, inveterately, angularity, breach of warranty, cellularity, chemotherapy, chrysotherapy, circularity, familiarity, granularity, hydrotherapy, incoherency, incoherently, insincerity, jocularity, lobularity, militarily, momentarily, necessarily, ordinarily, paper currency, popularity, psychotherapy, regularity, secondarily, serotherapy, serum therapy, similarity, singularity, solidarity, temporarily, voluntarily, with authority, x-ray therapy

6 syllables:
actinotherapy, ambidexterity, aversion therapy, behavior therapy, civil authority, complementarity, dissimilarity, dramatic irony, extemporarily, extraordinarily, fractional currency, implosion therapy, involuntarily, irregularity, letter security, listed security, particularity, peculiarity, physical therapy, physiotherapy, public security, radiotherapy, radium therapy, rectangularity, semitransparency, social security, socratic irony, supreme authority, triangularity, unfamiliarity, unregularity, unsimilarity

7 syllables:
absolute majority, agency security, collective security, electroshock therapy, government security, hypercellularity, hypocellularity, insulin shock therapy, manual dexterity, perpendicularity, radiation therapy, registered security, relative majority, unlisted security

8 syllables:
comptroller of the currency, conservation of parity, convertible security, occupational therapy

9 syllables:
over the counter security, redevelopment authority, regulatory authority

10 syllables:
breach of the covenant of warranty, geometrical regularity

11 syllables:
geometrical irregularity