2 syllables:
beaters, cheaters, eaters, greeters, heaters, liters, litres, meters, metres, peeters, peter's, peters, pieters, praetors, skeeters, streeters, teeter's, teeters, teters, treaters, tweeters

3 syllables:
100 meters, 100 metres, ammeters, anteaters, bee-eaters, beefeaters, completers, depleters, eggbeaters, fire-eaters, fisheaters, maltreaters, man-eaters, mcfeeters, mcpeters, mcpheeters, ohmmeters, repeaters, seedeaters, two-seaters, ureters, voltmeters, wattmeters, windcheaters, world-beaters

4 syllables:
1500 metres, 200 metres, 400 metres, 60 metres, 800 metres, bolometers, ceilometers, centiliters, centilitres, centimeters, centimetres, clinometers, cyclometers, decalitres, decametres, deciliters, decilitres, decimeters, decimetres, densimeters, ergometers, evan peters, femtometres, fluorimeters, gasometers, gravimeters, hectolitres, hectometres, honeyeaters, hypsometers, kilolitres, kilometers, kilometres, lotus-eaters, manometers, megalitres, micrometres, milliammeters, milliliters, millilitres, millimeters, millimetres, multimeters, nanometers, nanometres, overeaters, oximeters, pedometers, planimeters, planometers, russell peters, sonometers, superheaters, tachometers, tachymeters, taximeters, telemeters, tetrameters, tonometers

5 syllables:
5000 metres, actinometers, bernadette peters, galvanometers, inclinometers, piezometers, reflectometers, salinometers, velocimeters

6 syllables:
sphygmomanometers