3 syllables:
causator

4 syllables:
compositor, depositar, depositor, dispositor, repositor

5 syllables:
ovipositor

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, commoner, nonpolar, pothunter, conifer, nothosaur, gossiper, slopseller, chronicler, dropkicker, hop-picker, moniker, polisher, polypore, rotifer, shoplifter, somme river

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, admonisher, barometer, canopic jar, photometer

5 syllables:
interlocutor, lexicographer, gas thermometer, salinometer, densitometer, myriameter, choreographer, piezometer, variometer, dynamometer, anemometer, katharometer, mass spectrometer, audiometer, mileometer, vinyl polymer, goniometer, galvanometer, sensitometer, inclinometer, actinometer, declinometer, tacheometer, magnetometer, tensiometer

6 syllables:
interferometer, autobiographer, accelerometer, cinematographer, sphygmomanometer, evaporometer, telethermometer, microphotometer, spectrophotometer

7 syllables:
clinical thermometer, resistance thermometer, radiomicrometer, mercury barometer

8 syllables:
electrodynamometer

9 syllables:
radio interferometer