3 syllables:
chthonian, cronian, tonian, zonian

4 syllables:
adonean, andonian, antonian, aonian, ausonian, baconian, bathonian, bergsonian, bezonian, bosconian, bostonian, brunonian, capetonian, catonian, chelonian, clactonian, clintonian, corkonian, daltonian, demonian, devonian, dobsonian, draconian, dundonian, eonian, esthonian, estonian, etonian, favonian, franconian, glyconian, gorgonian, hasmonean, houstonian, hudsonian, huttonian, ionian, jacksonian, johnsonian, jonsonian, laconian, lapponian, leonian, melkonian, miltonian, neronian, newtonian, ottonian, oxonian, pannonian, pavonian, plutonian, pyrrhonean, pyrrhonian, samsonian, sardonian, scillonian, sclavonian, senonian, shaconian, shoshonean, shoshonian, sidonian, simonian, slavonian, smithsonian, solonian, tenonian, thomsonian, tironian, tithonian, tortonian, trentonian, trophonian, tsakonian, usonian, wilsonian

5 syllables:
abelonian, aberdonian, acheronian, addisonian, amazonian, apollonian, arizonian, babylonian, babylonien, caledonian, calypsonian, catachthonian, ciceronian, colophonian, emersonian, haligonian, hamiltonian, heliconian, hutchunsonian, jagiellonian, jeffersonian, macaronian, madisonian, mamikonian, muggletonian, myrmidonian, oregonian, pacchionian, paphlagonian, parkinsonian, patagonian, saint-simonian, sturionian, tennysonian, tettigonian, tobagonian, torontonian, vandemonian, washingtonian

6 syllables:
lacedaemonian

8 syllables:
assyro-babylonian

3 syllables:
goethian

4 syllables:
custodian, cambodian, napoleon, utopian, antipodean, dystopian, mongolian, eolian, dostoevskian, tyrolean, zoroastrian

5 syllables:
nickelodeon, theologian, anatolian, antinomian, ethiopian, phycocyanin, philibosian