3 syllables:
dominar, dominer, nominor, promener

4 syllables:
uncommoner

5 syllables:
fellow-commoner

6 syllables:
gentleman-commoner

3 syllables:
brontosaur, sloganeer, hosteller, monitor, hollander, godmother, nodular, polymer, proposer, jocular, cockchafer, sodbuster, popular, cocklebur, modeler, hogchoker, goddaughter, commodore, colander, columnar, alcazar, oliver, blockbuster, pompadour, bolivar, gospeler, modeller, monomer, commissar, globular, onager, almoner, stomacher, gobbler, gossamer, nonpolar, pothunter, conifer, nothosaur, gossiper, slopseller, common murre, cottager, gospeller, groveller, holloware, ocular, promiser, promisor, quadrature, swashbuckler, troposphere, wobbler

4 syllables:
biographer, atmometer, picometer, spectrometer, cryometer, psychrometer, tachometer, spherometer, manometer, astronomer, algometer, hodometer, unpopular, decametre, bilocular, demographer, photographer, pornographer, binocular, clinometer, bolometer, philosopher, kilometer, astrologer, speedometer, subocular, thermometer, geographer, reconciler, odometer, siphonophore, hygrometer, chronometer, micrometer, hydrometer, assam rubber, black hollander, compositor, copolymer, cosmographer, dock-walloper, ethnographer, femtometer, geometer, heart monitor, hectometer, horologer, involucre, lithographer, pedometer, pisanosaur, pyrometer, sclerometer, tintometer, typographer, viscometer

5 syllables:
interlocutor, lexicographer, gas thermometer, salinometer, densitometer, myriameter, choreographer, piezometer, variometer, ovipositor, dynamometer, anemometer, katharometer, mass spectrometer, audiometer, mileometer, vinyl polymer, goniometer, galvanometer, sensitometer, inclinometer, actinometer, declinometer, tacheometer, magnetometer, air thermometer, bibliographer, craniometer, electrometer, eudiometer, meat thermometer, oceanographer, press photographer, radiographer, radiometer, refractometer, simon bolivar

6 syllables:
interferometer, autobiographer, accelerometer, cinematographer, sphygmomanometer, evaporometer, telethermometer, african monitor, beckman thermometer, candy thermometer, cardiac monitor, cubic kilometer, historiographer, oven thermometer, platinum thermometer, potentiometer, silicone polymer, thermohydrometer

7 syllables:
clinical thermometer, resistance thermometer, radiomicrometer, centigrade thermometer, electric thermometer, fahrenheit thermometer, mercury thermometer, political commissar, reversing thermometer, vernier micrometer

8 syllables:
electrodynamometer

9 syllables:
radio interferometer, electronic fetal monitor

11 syllables:
maximum and minimum thermometer