3 syllables:
valvular

4 syllables:
avalvular

3 syllables:
agateware, gatecrasher, alcazar, almoner, blockbuster, bolivar, cocklebur, colander, columnar, commissar, commodore, commoner, common murre, conifer, cottager, globular, gobbler, godmother, gospeler, gospeller, gossamer, gossiper, groveller, hollander, holloware, hosteller, jocular, modeler, monitor, monomer, nodular, ocular, oliver, onager, polymer, pompadour, popular, promiser, promisor, quadrature, slopseller, sodbuster, swashbuckler, troposphere, wobbler

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

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

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

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

8 syllables:
electrodynamometer

9 syllables:
electronic fetal monitor, radio interferometer

11 syllables:
maximum and minimum thermometer