1 syllable:
'em, 'm, -some, bd-rom, bluhm, brum, brumm, bum, chum, clum, cm sm, come, comme, crum, crumb, crumm, csc ssm, cum, ddrum, druim, drum, drumm, dslam, dum, dumb, dumm, dzbb-am, dzrj-am, from, frum, fsk im, gd-rom, glum, gmbh, gmm sm, grum, gthumb, gum, gumm, hb gam, hm, hmm, hp tim, hrtem, hum, humm, jlc csm, jpcg dimm, jstars gsm, khnum, klumb, krum, krumm, krumme, kumm, lum, lumb, lumm, lumme, lv sem, maam, mp gam, msd sm, msn im, mum, mumm, mumme, nccam, nd tem, ngcam, ns qam, numb, pflum, phlem, phleme, plum, plumb, pps sm, rhomb, rs tim, rum, schem, schrum, schtum, schum, schumm, scrum, scum, scumm, shrum, shtum, shum, skrim, slum, smd imb, smram, some, spf dbim, sp tcim, std ssm, strum, stum, stumm, stumme, sum, summe, swum, them, thrum, thum, thumb, thumm, tp fem, tshombe, um, umm, v-comb, vl-srsam, xrsam, yum, bloom, blue&me, blum, blume, boom, boomm, broom, broome, brume, bthoom, choom, cloom, coomb, coombe, croom, crume, cu mm, dhoom, doom, droom, flume, froom, fume, gloom, glume, groom, groome, grume, heaume, hume, krume, kume, loom, neume, plume, pneum, reaume, rewme, rheaume, rheum, rhumb, rhume, room, roome, sh-boom, shoom, shroom, shtoom, sloom, spoom, spume, stoom, stroom, suhm, tomb, tombe, vroom, vroomm, whom, womb, zoom

2 syllables:
aksum, alum, ancrum, bass drum, baucum, bay rum, beach plum, become, benumb, bethumb, bithumb, black gum, blue gum, boyum, brake drum, branscome, breadcrumb, cancrum, carum, checksum, columb, date from, date plum, dishyum, djarum, encom, exum, faiyum, first-come, flow from, freedumb, ghost gum, goodrum, goose plum, green thumb, guthrum, herefrom, hog plum, hohum, hop-thumb, how come, humdrum, ikwum, income, keep from, keep mum, kim bum, larum, lump-sum, marum, mccrum, mccrumb, narum, neu-ulm, noucome, outcome, pileum, plethrum, pond scum, red drum, red gum, rose gum, sharum, shrink from, side drum, snare drum, snow gum, steak-umm, steel drum, stepmom, striped drum, succumb, swamp gum, sweet gum, tear-thumb, tecum, therefrom, tom thumb, unplumb, wellcome, wherefrom, wild plum, wring from, yab-yum, yum-yum, yumyum, abloom, absume, addoom, agrume, artume, assume, backroom, back room, ballroom, barroom, bath-room, bathroom, batoum, bedroom, bitume, boardroom, box-room, boxroom, bridegroom, broadloom, bunkroom, busboom, by-room, cardroom, changeroom, chatroom, chat room, checkroom, child's room, classroom, clean-room, cleanroom, clean room, cloakroom, clubroom, coatroom, consume, cookroom, cornblume, costume, courtroom, coutume, darkbloom, darkroom, dayroom, dead room, death-doom, deplume, despume, displume, dorm room, drawloom, effume, embloom, emplume, enclume, engloom, entomb, enwomb, exhume, feldblum, fireroom, front room, game room, green-broom, greenroom, green broom, grillroom, guardroom, guestroom, gunroom, gun room, handloom, headroom, heirloom, herdgroom, homeroom, houseroom, icewm, illume, inhume, insume, intomb, jib-boom, jibboom, ka-boom, kaboom, keurboom, khartoum, laboum, laplume, legroom, legum, legume, lightroom, lindbloom, lunchroom, macroom, mailroom, maktoum, maybloom, mcbroom, men's room, mf doom, mtume, mudroom, mydoom, naboom, natsume, newsroom, okoume, outroom, pantoum, parfum, parfume, perfume, playroom, poolroom, pressroom, presume, pump room, push broom, raceroom, rebloom, rec room, reillume, relume, restroom, resume, reume, roseboom, royaume, salesroom, salume, schoolroom, scotch broom, sea room, showroom, sickroom, simoom, spekboom, staffroom, stateroom, steam room, stillroom, still room, stockroom, stock room, storeroom, strongroom, subsume, sukhum, sumoom, sunroom, sweat room, tap-room, taproom, tearoom, test room, toolroom, transhume, transume, ubume, unplume, untomb, varoom, wardroom, wareroom, warkloom, washroom, wash room, weightroom, whiskbroom, white broom, white room, witch broom, workroom

3 syllables:
abstain from, adnexum, amarum, amphicome, august plum, barathrum, beetlebum, bongo drum, bubble gum, bungarum, cherry plum, chewing gum, cider gum, cocoa plum, coco plum, common plum, congo gum, damson plum, deaf-and-dumb, desist from, direct sum, disbecome, escape from, flooded gum, labarum, manna gum, mesquite gum, metal drum, misbecome, mishawum, moxie plum, natal plum, net income, no-see-um, norodom, obesum, overcome, physarum, podarthrum, pyrethrum, refrain from, river gum, rule-of-thumb, rule of thumb, saccharum, sisarum, sour gum, spirit gum, spotted gum, tartarum, tax income, tenor drum, tidy sum, time to come, unbecome, unbenumb, vector sum, water gum, zero-sum, a400m, after-room, alumbloom, ante-room, anteroom, apostume, baby's room, baby-boom, baby boom, badaboom, billiard room, boiler-room, breathing room, butcher's broom, carpet loom, cfu-m, coffeeroom, common-room, common broom, common room, control room, corniplume, cutting room, daremblum, desert plume, dining-room, diningroom, dining room, disentomb, disinhume, disselboom, drawing-room, drawing room, dressing-room, dressing room, elbow-room, elbowroom, elbow room, engine room, figure loom, filoplume, foredoom, furnace room, georgia groome, groovyroom, hecatomb, hotel room, impostume, introsume, isohume, ladies' room, lecture room, legalzoom, living-room, livingroom, living room, locker-room, lockerroom, locker room, low-warp-loom, lumber-room, lumber room, messroom, morning room, motel room, nom de plume, nutriboom, overgloom, pernille blume, petalum, potchefstroom, powder room, power loom, re-assume, reading room, reassume, ringelblume, rosenbloom, rosenblum, rosenboom, rozeboom, saleroom, scarlet plume, seating room, semiplume, sewing room, shipping room, shower room, silverboom, sitting-room, sitting room, sleeping room, smoking room, sonic boom, sonnenblume, spanish broom, standing room, storage room, testing room, tiring-room, tv room, vandenboom, wagenboom, waiting room, weaver's broom, womb-to-tomb, yubitsume

4 syllables:
abomasum, arisarum, canada plum, carissa plum, chickasaw plum, dante exum, erucifrom, falciparum, forest red gum, glyoxysome, governor's plum, governor plum, granulosum, hedysarum, hop-o'-my-thumb, jamaica rum, japanese plum, marmalade plum, mountain swamp gum, pacific plum, peppermint gum, pigmentosum, principal sum, river red gum, senegal gum, shy away from, sierra plum, sonora gum, stay away from, stenotaphrum, the world to come, unearned income, ame-no-uzume, artist's workroom, bathing costume, brodifacoum, chaparral broom, conference room, electroboom, family room, google classroom, hospital room, indigo broom, kemonozume, master bedroom, microphone boom, monster musume, overconsume, reception room, recovery room, s1850m, swimming costume, the viper room, weeping tree broom, white spanish broom, withdrawing-room, withdrawing room

5 syllables:
alleghany plum, allegheny plum, eucalyptus gum, government income, madagascar plum, national income, personal income, tetrapharmacum, whatever may come, 5.8x42mm, adobe lightroom, dormitory room, dynamic headroom, emergency room, masquerade costume, nehruviandoom, operating room, recreation room, television room

6 syllables:
american red plum, american sweet gum, disposable income, oleosaccharum, per capita income, academic costume

7 syllables:
assassination classroom

8 syllables:
universal basic income