1 syllable:
.hack, ack, akc, back, backe, bak, bakke, blacc, black, blaque, brac, brack, brakke, braque, cac, caq, caque, cb wcac, cg fmfpac, chack, chaque, clack, claque, crack, craque, crme frache, dac, dack, dak, dmacc, drack, dsmac, fac, flack, flak, flaque, frack, h-back, h-gac, hack, hacke, haq, haque, httrack, jac, jack, jacke, jacques, jaque, ka'ak, kacke, kakke, knack, krack, kracke, kwak, lac, lacche, lack, lak, lakke, laque, mac, mack, macke, mak, mblaq, nack, nacke, ncpac, njpac, nlnac, pac, pack, pakke, paque, pbkac, phrack, plack, placke, placque, plaque, plbkac, ptak, quack, quaque, rack, rak, rtfaq, sac, sack, sacque, sak, schach, schack, schlack, schnack, schrack, shack, shaq, slack, smack, snacc, snack, spack, spak, sprack, stac, stack, strac, strack, stracke, strak, tac, tack, tacke, tak, takk..., taque, thack, thrack, thrak, tplac, trac, track, trak, tslaq, t a c, wack, wacke, whack, wrack, yack, yak, zach, zack, zak

2 syllables:
6lack, aback, abaque, adak, aflac, aipac, air sac, all-trac, alsac, amtrac, amtrack, anfac, anzac, apsac, arnaque, assjack, ataque, attac, attack, attaque, auerback, austrac, backpack, backrack, backtrack, ballsack, bar-back, bareback, barmbrack, barnbrack, beat back, beaulac, bidlack, binac, bipac, bipack, black-jack, blackjack, blowback, blu-tack, blue-black, blueback, bluejack, blue jack, boback, bombtrack, bomb rack, boneblack, bookstack, bootblack, bootjack, bounceback, bounce back, bring back, brown-black, brownback, brumback, brushback, bushwhack, buttcrack, buy-back, buyback, call-back, callback, call back, calpac, calpack, capac, carjack, cart track, cash-back, cashback, cepac, champac, chargeback, cheap-jack, cheapjack, checkback, chi-raq, chirac, choke back, chyack, cincpac, clawback, click-clack, coal-black, coal black, coatrack, cognac, colemak, come-back, comeback, comeblack, come back, compaq, cookshack, countback, creashak, crookback, crossjack, cutback, cuttack, cut back, date back, daypack, deathtrack, deepak, deltak, die-back, dieback, die back, dirac, dirt track, dish rack, drawback, draw back, dress rack, drive back, dropback, drop back, dulac, dysac, eastpac, eastpak, eclac, ellac, estrack, eyeblack, face pack, failback, fall-back, fallback, fall back, fast-track, fastback, fastrack, fasttrack, fatback, feeback, feed-back, feedback, feed back, fightback, fight back, finback, fintrac, firaaq, fishback, fitak, flapjack, flareback, flashback, flash back, flat-pack, flatback, flatpack, flatpak, flowback, flyback, foldback, forblack, force back, foreslack, formac, formstack, forslack, fosback, full-back, fullback, gaillac, gempak, gernsback, get back, gimcrack, giveback, give back, glasspack, godsmack, gopac, gopak, govtrack, go back, grass wrack, gray-black, grayback, greenback, grey-black, greyback, grimjack, gripsack, gum-lac, gun-nac, half-back, half-track, halfback, halftrack, half track, hanback, hang back, harac, hard-tack, hardback, hark back, hatchback, hatrack, haystack, haystak, hi-jack, hibaaq, highjack, hijack, hipac, hitchrack, hoback, hogback, holdback, hold back, hopsack, hornback, hornwrack, horseback, humpback, hunchback, icepack, ice pack, immac, impac, ink-black, ipecac, itaque, jack black, jam-pack, jampac, jamstack, jet-black, jetpac, jetpack, jet black, jimcrack, kalpac, kammback, kecak, keep back, kickback, kick back, killpack, knapsack, knick-knack, knickknack, knitback, knock-back, knockback, knock back, kodak, kojak, kyack, l0phtcrack, laid-back, laidback, lampblack, lapack, larzac, layback, lean back, leaseback, left-back, lifehack, liftback, lilac, lineback, linpack, lojack, look back, loopback, lootpack, macpac, mafac, malac, manjack, man jack, masback, matlack, mauzac, medac, mi'kmaq, midac, midpac, mikmaq, mirfac, mossback, mostack, move back, mudpack, muntjak, musac, mustac, n-back, nadac, navfac, netback, nethack, niblack, nonblack, nopac, notchback, nyack, oblak, ocpac, off-the-rack, off-track, offtrack, one-track, ontak, oopack, ophcrack, outback, packsack, padak, page-jack, pauraque, payback, pay back, peapack, pebcac, pebcak, pebmac, persac, phone jack, pickback, pickpack, pillpack, pinback, pinchback, pingback, pipe rack, pitch-black, pitch black, plate rack, playback, play back, plowback, pofac, poltrack, prepack, presspack, prozac, pull-back, pullback, pull back, pumpjack, pushback, push back, put back, quillback, racetrac, racetrack, radak, railsback, railtrack, rakeback, rakshak, ramdac, ransack, ratpack, reachback, rear back, redback, redhack, rempac, repack, ricrac, ridgeback, right-back, rimpac, ringback, roback, rojak, rollback, roof rack, roorback, roundback, rowback, ruback, rucksack, runback, ryback, sadak, sad sack, sand crack, scaleback, scatback, schupak, scratchback, screw jack, sea-tac, seatback, sea wrack, sedac, seed-lac, seed lac, send back, sepaq, set-back, setback, set back, shane black, sheepback, shell-lac, shellac, shellack, shellback, shishak, shoeblack, shoepac, shoepack, shoe black, shopback, shriekback, shrink-pack, shrink back, sidetrack, sifac, simpac, sit back, six-pack, sixpack, skewback, skimback, skipjack, ski rack, skyjack, slapjack, slate-black, slayback, sling-back, slingback, slotback, slowback, smarttrack, smokejack, smokestack, snapback, snapsack, snowpack, socpac, soft-tack, softback, soot-black, soot black, soundtrack, sowback, spice rack, spiewak, spineback, splashback, spore sac, spur track, sremac, stainback, stanback, stand back, startrack, steinback, stick-lac, stick lac, stoneback, strickjacke, strongback, substack, sunback, supac, supplejack, swartback, swayback, sweepback, swept-back, sweptback, switchback, t-back, tabac, tabak, tailback, take back, talk-back, talkback, tarmac, tear sac, termac, thakshak, think back, thornback, throwback, throw back, thumb-tack, thumbtack, tic-tac, tick-tack, ticktack, tictac, tieback, tie rack, tie tack, tintack, toastrack, toe crack, toothback, toss back, touchback, towsack, trackback, transpac, triac, tricktrack, trictrac, trim back, tritac, trunkback, tuqaq, turnback, turn back, two-track, undac, unpack, unstack, untack, uzmack, vanvlack, wakwak, wanaque, wavpack, wayback, webpack, wejack, welsh black, wesak, wespac, westpac, wewak, whaleback, whipjack, whiteback, whitenack, winback, wingback, win back, wisecrack, wolf-pac, wolf-pack, wolfpack, wolf pack, woolpack, write-back, x-pac, yolk-sac, yolk sac

3 syllables:
-maniac, afrojack, ahorseback, air attack, al-boraq, algonac, almanac, almanach, almanack, almanaque, amberjack, andromaque, annie mac, anorak, answerback, anti-black, antiblack, apple-jack, applejack, aurolac, autofac, autorack, back-to-back, back in black, bernie mac, bible black, biopack, black-on-black, bladderwrack, blister pack, blue-lilac, bluish-black, bosniac, bottle-jack, box kodak, brainiac, break one's back, brownish-black, browserstack, bubble pack, bumper jack, caddyshack, cadilac, cadillac, camelback, canvas-back, canvasback, carbon black, cardiac, cardiaque, carpet tack, carry-back, carryback, carry back, cdiac, ceding back, centre-back, chimneystack, christian-jaque, cilla black, cinder track, cinepak, cluniac, colby-jack, coming back, computrac, comsubpac, condillac, cornerback, crackajack, cracker-jack, crackerjack, cul-de-sac, culs-de-sac, cul de sac, data track, dental plaque, diamond-back, diamondback, doodlesack, dottyback, double-back, doubleback, double back, do not track, drekavac, dressing sack, dynafac, dynapac, easiac, ebufac, eniac, fatigue crack, featherback, fiddle-back, fiddleback, fireback, fishing smack, flankerback, fragmentak, freddie mac, freejack, from way back, garnet lac, googlewhack, ground attack, grzelak, gunnysack, gunny sack, hackensack, hackleback, hackmatack, halter-sack, heartattack, heart attack, helitack, high-low-jack, hit the sack, hollenback, hollow-back, holsomback, holsonback, huckaback, hydrocrack, ianac, idrac, ileac, indo-pak, iniac, inky-black, innopac, inside track, interac, iupac, jiffi-snak, jon matlack, jumping jack, karen black, kodak black, kodiak, kozemchak, kvelertak, ladder-back, lancejack, lazyback, leatherback, leatherjack, lobsterback, louderback, lucas black, luggage rack, lumberjack, macisaac, magicjack, mahopac, malinak, maniac, marforpac, medivac, meet joe black, merrimack, messagepack, minitrack, minute-jack, mitilac, mondotrack, money-back, moniac, mosiac, msiac, muharraq, multipack, multitrack, murtabak, music rack, narrowback, natterjack, nickajack, nickelback, nordictrack, openstack, oplenac, orphan black, overpack, pac-attack, paddywhack, paperback, paranaque, paying back, perl-byacc, petrofac, pickaback, pickapack, pickleback, pig-a-back, piggyback, platinum black, pontiac, post-attack, power pack, prickleback, purple-black, qaanaaq, quarterback, quarter crack, racerback, radiac, railroad track, rattleback, razorback, ride horseback, rose-lilac, running back, saddleback, sangiac, screwattack, sechserpack, senlac, sexyback, shediac, silverback, similac, similack, simulac, single-track, singletrac, singletrack, sooty-black, steeplejack, stickleback, stock buyback, streetcar track, sulindac, supermac, supple-jack, tac-au-tac, tacmahack, take aback, tenure-track, timberjack, tlaquepaque, tori black, towel rack, tupilaq, turtleback, union jack, uummannaq, vantablack, waguespack, warty-back, water back, whisker jack, wolenzac, woollyback, wurdulac, yellowback, yellow jack, zodiac, zodiak

4 syllables:
abrar-ul-haq, acardiac, aleister black, amarkantak, ammoniac, amnesiac, aphasiac, armoniac, asthma attack, audiomack, bicycle rack, bioattack, biofeedback, bluish-lilac, bongcloud attack, brute-force attack, calicoback, caroline flack, chanie wenjack, clickety-clack, common lilac, comnavairpac, coronavac, counter-attack, counterattack, cyberattack, daemoniac, demoniac, dowagiac, dustin lance black, elegiac, etodolac, frontiniac, getdataback, imam-ul-haq, inaamulhaq, insomniac, ivory black, magazine rack, misbah-ul-haq, monbazillac, narsarsuaq, neurofeedback, noncardiac, paige spiranac, panic attack, paranoiac, paul-peter tak, pelusiac, persian lilac, plan of attack, precardiac, purple-lilac, qikiqtarjuaq, radioshack, rejuvelac, roger lloyd-pack, samurai jack, serrated wrack, service cutback, simoniac, sonora lac, surprise attack, symposiac, telephone jack, under attack

5 syllables:
angle of attack, anglomaniac, anthomaniac, aphrodesiac, bacterial plaque, bradycardiac, chinese zodiac, diplocardiac, dipsomaniac, endocardiac, epicardiac, ergomaniac, exocardiac, hypospadiac, intracardiac, inzamam-ul-haq, japanese lilac, literary hack, logomaniac, meglomaniac, melomaniac, metromaniac, monomaniac, mythomaniac, need for speed payback, negative feedback, nymphomaniac, off the beaten track, pandemoniac, pericardiac, political hack, positive feedback, pryromaniac, pyromaniac, radio-opaque, sal-ammoniac, salammoniac, tachycardiac, theomaniac, warning of attack

6 syllables:
anxiety attack, beynac-et-cazenac, bibliomaniac, himalayan lilac, hungarian lilac, japanese tree lilac, man-in-the-middle attack, megalomaniac, orange is the new black, sign of the zodiac, the empire strikes back, toronto van attack, tulipomaniac

7 syllables:
akshardham temple attack, diversionary attack, eleutheromaniac

8 syllables:
denial-of-service attack, miami cannibal attack, wannacry ransomware attack

9 syllables:
tokyo subway sarin attack

10 syllables:
2012 benghazi attack, kyoto animation arson attack