2 syllables:
-ator, aitor, ater, baiter, bater, cater, clater, claytor, crater, cratere, dater, dator, eighter, flater, frater, freighter, gaiter, gater, gator, gaytre, grater, greater, hater, hate her, hayter, kater, krater, kreator, later, maatr, maatre, mater, matre, nater, pater, patre, plaiter, plater, prater, praytor, quatre, rater, sator, satre, schlater, skater, slater, slayter, sleator, stater, stator, straighter, strater, tater, tator, traiter, traitor, trator, vater, vator, waiter, waitr, yater

3 syllables:
abater, abator, abatur, ablator, acater, affreighter, allaiter, archtraitor, await her, ballater, barrater, bay stater, bellator, castrater, castrator, citator, collator, constater, creator, curator, debater, debatir, debator, decatur, deflater, deflator, dictator, diktator, dilater, dilator, donator, downstater, dumb-waiter, dumbwaiter, embratur, epater, equater, equator, fellator, first-rater, fixator, forfaiter, frustrater, glossator, grallator, gyrator, headwaiter, head waiter, hostgator, hydrator, ice-skater, inflater, inflator, jew-baiter, landwaiter, lemaitre, levator, ligator, linklater, locator, mandator, mercator, migrator, misater, mutator, narrater, necator, negator, nitrator, notator, novator, pdfcreator, piscator, pond-skater, potator, probator, pronator, prostrator, pulsator, punctator, racetraitor, rapator, rebater, regrater, regrator, relater, relator, rotator, saltator, sea slater, serrator, shad-waiter, sopater, speedskater, tailgater, testator, third-rater, titrator, translater, translator, tronator, updater, upstater, vacatur, vanmatre, viator, wine waiter, zoolater

4 syllables:
abdicator, abnegator, abrogator, activator, actuator, adminstrator, adulator, advocator, agadmator, aggravator, agistator, agitator, akinator, aligator, allegator, alligator, allocator, allocatur, alternator, ambulator, amputator, animator, annotator, applicator, approbator, arbitrator, arborator, archiater, arendator, arpentator, arrogator, aspirator, astrogator, astrolater, auktionator, auscultator, aviator, baconator, bardolater, bloviator, brusselator, buccinator, cachinnator, calculator, calibrater, calibrator, captivator, carbonator, carburator, carburetor, castigator, celebrater, celebrator, chicxulub crater, chlorinator, cinerator, circulator, cogitator, combinator, commendator, commentator, commutator, companator, compensator, compilator, compotator, compurgator, concentrator, conciator, confiscator, congregator, congress gaiter, conjugator, conjurator, consecrater, consecrator, consolator, consummator, contemplator, convocator, corporator, correlator, corrugator, criminator, cultivator, cybernator, decimator, declamator, decollator, decorator, dedicator, defalcator, defecator, delegator, demarcator, demonstrater, demonstrator, denigrator, dephlegmator, deprecator, depredator, deputator, desecrater, desecrator, designator, desolator, detonator, devastator, deviator, dilatator, dissertator, dissipater, dissipator, divinator, dominator, duplicator, educator, elevator, emanator, emendator, emigrator, emulator, epilator, escalator, escheator, estimator, evocator, excavator, excitator, expiator, expilator, explicator, exsiccator, extirpator, fabricator, fabulator, fascinator, figure-skater, flagellator, formulator, fornicator, fractionator, fulminator, fumigator, generator, germinator, gladiator, gonkulator, governator, graduator, granulator, gurgitator, habitator, hesitater, hesitator, hibernator, idolater, idolator, illustrator, imitater, imitator, immolator, imprecator, impregnator, incarnator, incubator, inculcator, indagator, indicator, infiltrator, inhalator, innovator, inspirator, inspissator, instigator, instillator, instilllator, insufflator, insulator, integrator, intubator, inundator, irrigator, irritator, isolator, iterator, jaculator, jetavator, joculator, judicator, jugulator, kegerator, kelvinator, lachrymator, lacrimator, laminator, lapidator, legislator, levitator, liquidator, literator, litigator, lubricator, lunar crater, macerator, machinator, malaxator, masticater, masticator, masturbator, mediator, medicator, meditator, meliorater, meliorator, metadate er, methylator, mitigator, moderator, modulator, monolater, motograter, mutilator, mystificator, navigator, nomenclator, nominator, nucleator, numerator, obfuscator, objurgator, obligator, obturator, obviator, operator, orchestrator, ordinator, oscillator, osculator, ostentator, out-of-stater, oxidator, ozonator, peculator, penetrator, percolator, perforator, permeator, permulator, perpetrator, personator, perturbator, phabricator, pollinator, populator, postillator, postulator, predicator, procreator, promulgator, propagator, protestator, punctuator, rabiator, radiator, rectificator, regulator, remonstrator, renovator, replicator, resonator, respirator, revelator, roller-skater, rotavator, rotovator, rubricator, ruminator, rusticator, salivator, saturater, saturator, scintillator, second-rater, segregator, selling-plater, separator, seperator, sequenator, sequestrator, simulator, sosipater, speculator, spoliator, stabilator, stellarator, stimulater, stimulator, stipulator, stridulator, subjugator, suffragator, sulphurator, summercater, superfreighter, supinator, supplicator, syncopator, syndicator, tabulator, telestrator, telustrator, terminator, testificator, titillater, titillator, tolerator, trafficator, transformator, travelator, travolator, triturator, twerkulator, undulator, urinator, vacillator, valuator, venerator, ventilator, ventilatore, verilator, vindicator, violator, water skater, wheelabrator, whizzinator, woman-hater, woman hater, wurstelprater

5 syllables:
28 days later, 28 weeks later, abbreviator, aberuncator, abominator, accelerator, accommodator, accumulator, achillobator, adjudicator, administrator, adulterator, agglomerator, alienator, alleviator, alliterator, amalgamator, ameliorator, amphitheater, amphitheatre, annihilator, anticipator, appreciator, appropriator, approximator, arcovenator, arpeggiator, articulator, asphyxiator, assassinator, asseverator, assimilator, associator, attenuator, authenticator, averruncator, bibliolater, bronchodilator, calorisator, calumniator, capitulator, centuriator, christophe lemaitre, co-operator, co-ordinator, coagulator, cogenerator, collaborator, commemorator, commiserator, communicator, concavenator, conciliator, confabulator, confederator, conglomerator, congratulator, considerator, consolidator, contaminator, continuator, cooperator, coordinator, corroborator, deactivator, decapitator, decelerator, decorticator, defibrillator, defoliator, degerminator, deliberator, delineator, demodulator, demonolater, denominator, denunciator, depopulator, depreciator, desalinator, determinator, dilapidator, discriminator, disintegrator, disseminator, dissimulator, domesticator, dracovenator, edulcorator, ejaculator, elaborator, electroplater, eliminator, elucidator, elutriator, emancipator, emasculator, encapsulator, enucleator, enumerator, enunciator, epitomator, equivocator, eradicator, evacuator, evaluator, evaporator, eviscerator, exaggerator, examinator, exasperater, excelerator, excogitator, excoriator, exhilarator, exonerator, expatiator, expostulator, expropriator, extenuator, exterminator, extrapolator, facilitator, falsificator, felicitator, flight indicator, flight simulator, flux applicator, food elevator, freight elevator, full radiator, gesticulator, growth regulator, habilitator, hagiolater, hand calculator, house decorator, humiliator, hypothecator, iconolater, illuminator, imperobator, impropriator, improvisator, inaugurator, incarcerator, incinerator, incorporator, incriminator, indoctrinator, inoculator, inseminator, insidiator, interpellator, interpolator, interrogator, intimidator, invalidator, investigator, invigilator, invigorator, irradiator, justificator, legitimator, manipulator, modificator, monochromator, multiplicator, nash-kelvinator, negotiator, neverthelater, obliterator, officiator, opiniator, opinionator, optoisolator, originator, oxygenator, pacificator, perambulator, peregrinator, perpetuator, pontificater, pontificator, potentiator, precipitator, predestinator, predominator, prefabricator, premeditator, procrastinator, prognosticater, prognosticator, proliferator, pronunciator, pulse generator, purificator, qualificator, quartz oscillator, re-animator, reanimator, reciprocator, recriminator, recuperater, recuperator, redecorator, redintegrator, refridgerator, refrigerator, regenerator, regurgitator, rejuvenator, remunerator, repudiator, resuscitator, retaliator, reverberator, room decorator, sacrificator, sales demonstrator, scarificator, sermocinator, significator, somnambulator, sooner or later, sophisticator, speed indicator, stabilisator, subordinator, the great dictator, totalisator, totalizator, transliterator, turn indicator, vasodilator, vaticinator, versificator, vinificator, vituperator, wind generator

6 syllables:
aerogenerator, astronavigator, bioindicator, celestial equator, chinese alligator, circumnavigator, counterdemonstrator, crystal oscillator, darvaza gas crater, decontaminator, denitrificator, differentiator, dineobellator, disambiguator, disarticulator, engine-generator, excommunicator, experimentator, fuel indicator, genus alligator, ichthyovenator, individuator, intermediator, laplace operator, leading indicator, local oscillator, magnetic equator, nanogenerator, neuromodulator, neurostimulator, newsstand operator, noncooperator, opensimulator, opto-isolator, osmoregulator, owner-operator, paraeducator, pocket calculator, poweranimator, pump-oxygenator, ratiocinator, recapitulator, reinvigorator, service elevator, switchboard operator, teleoperator, thermoregulator, transilluminator, transubstantiator, turbogenerator, voltage regulator, yandere simulator

7 syllables:
common denominator, company operator, google authenticator, hyperaccumulator, immunomodulator, linear operator, micromanipulator, nitrovasodilator, oxygen concentrator, photocoagulator, private investigator, proton accelerator, rotary actuator, telegraph operator, telemanipulator, telephone operator, turboencabulator

8 syllables:
american alligator, electric refrigerator, electron accelerator, elevator operator, heterodyne oscillator, identity operator, immunopotentiator, induction accelerator, interior decorator, linear accelerator, microsoft flight simulator, particle accelerator, principal investigator, random number generator

9 syllables:
academic administrator, electrostatic generator, modulator-demodulator, thermoelectric generator

10 syllables:
tissue plasminogen activator

11 syllables:
microwave linear accelerator

3 syllables:
komondor, roadrunner, fomenter, goatsucker, opener, open-air, volt-ampere, stonecutter, lowlander, boneshaker, cloakmaker, homemaker, notepaper, rose chafer, tolltaker, wholesaler

4 syllables:
eye opener, unhoped-for, can opener, tin opener

5 syllables:
bottle opener, letter opener, oculomotor