1 letter:
l

2 letters:
el, l.

3 letters:
aol, bel, cel, del, ell, fel, gel, mel, nel, nfl, sel, tel, xml, zel

4 letters:
adel, akel, apel, arel, behl, cell, dell, ehle, elle, fehl, fell, frel, gehl, gell, guel, hehl, hell, itel, jell, kehl, kell, lehl, mehl, mell, mtel, nell, nepl, noel, pehl, pell, quel, sell, tell, vsel, well, yell, zell

5 letters:
abdel, accel, adele, adell, allel, amtel, ancel, anfal, ansel, ardel, armel, arvel, autel, avdel, batel, bedel, bejel, belle, botel, canel, carel, catel, ccxml, celle, chele, chell, clell, codel, coel-, coele, corel, crell, d.c.l, datel, ddr3l, decel, delle, devel, divel, dntel, dovel, drell, dsssl, dwele, dwell, ebxml, ectel, edell, entel, etcsl, excel, expel, extel, ezell, favel, felle, fidel, fitel, fixml, fjell, gabel, gidel, grell, gsell, helle, hotel, impel, incel, intel, iptel, irell, jelle, jijel, k-tel, kehle, kelle, kjell, knell, krell, kvell, kwell, lapel, lepel, lyell, maill, melle, metel, mhtml, mitel, mizel, morel, motel, msxml, mytel, nadel, natel, nelle, nevel, nobel, notel, nu.nl, octel, odell, oftel, ooxml, parel, patel, pcnsl, pelle, pinel, popel, prell, quell, rahel, ravel, rebel, reell, repel, rotel, rupel, sabel, savel, selle, shell, shtml, sitel, skell, smell, snell, spell, stele, stell, swell, tavel, telle, thele, titel, trell, vadsl, varel, vhdsl, vieil, welle, yelle, yotel, zelle, zumel

6 letters:
5-cell, accell, adelle, adwell, ahnell, alltel, aludel, amabel, anatel, ansell, antell, anwell, aparel, ardell, aspell, atwell, auquel, avenel, axelle, axtell, axwell, b-cell, barcel, befehl, befell, bendel, bethel, beutel, bodell, boltel, bortel, bovell, bowtel, bozell, bultel, burdel, burhel, cabell, cantel, carcel, carmel, cartel, carvel, cautel, cavell, centel, chanel, chelle, codell, compel, contel, cordel, corell, cosell, d-cell, danell, darvel, dentel, dirxml, dispel, dwelle, elwell, engaol, ezelle, fardel, farell, faupel, ferrel, fidele, flotel, formel, foxtel, gaelle, gintel, grelle, harpel, hazael, hillel, hormel, hotell, isabel, ishbel, ismell, isobel, janell, joelle, kal-el, kanell, kordel, kpelle, labell, lequel, lobell, loisel, lortel, manuel, marcel, markel, martel, matell, mattel, maxell, mckell, mentel, michel, miguel, mikkel, miquel, mirell, montel, mousel, nextel, niguel, noelle, novell, noxell, o'dell, ocelle, orabel, orwell, oswell, otwell, ozelle, pactel, pantel, pastel, pentel, propel, quelle, rafael, raguel, rangel, raquel, rebell, rebtel, resdel, resell, retell, ridell, rintel, riopel, ruelle, sardel, schell, seitel, sintel, skytel, soquel, stelle, stinel, strehl, sydell, syncml, t-cell, torell, tricel, udelle, unheal, unhele, unitel, unsell, unwell, upsell, upwell, uzzell, varvel, vaupel, vertel, vielle, viorel, visuel, weisel, wiltel, ysabel

7 letters:
24-cell, agnelle, aharhel, aimwell, aircell, airelle, alcatel, angelle, annabel, annelle, appelle, ardelle, arielle, arnelle, artcell, ashwell, assubel, attwell, babybel, bagwell, banwell, barbell, bardell, barwell, bechtel, bedwell, bidwell, bignell, bodwell, bonwell, bordell, boultel, boutell, bowbell, boxwell, brindel, burdell, burrell, buswell, buzzell, cadelle, cadfael, cadwell, calomel, capelle, capwell, caravel, carvell, carwell, caswell, cattell, caudell, cencall, chanell, chapell, charmel, citadel, cofetel, colwell, comptel, conwell, cordell, corelle, cornell, coryell, cotelle, cowbell, coxwell, cozumel, crocell, culwell, dalyell, danelle, daniele, darnell, decelle, decibel, develle, diallel, dispell, dodwell, einhell, ekpwele, elcotel, eldfell, endwell, epkwele, espinel, estelle, eustele, falwell, farwell, fascell, femelle, ficelle, fichtel, folwell, forelle, foxwell, frenzel, futrell, gabelle, garnell, gazelle, gestell, getwell, ginnell, giselle, graupel, hanwell, harwell, hipwell, hornell, indwell, infidel, inkwell, iredell, isabell, issabel, italtel, janelle, javelle, jazelle, jenelle, jonelle, jumelle, kapelle, kapitel, kidwell, kordell, labelle, lamelle, landell, laravel, laswell, lavelle, ledwell, lemelle, lengyel, lubitel, lynelle, lyocell, mabelle, madelle, mantell, manwell, marelle, martell, marvell, maxwell, mekelle, mendell, merisel, micelle, michele, mindell, minitel, mirabel, mirelle, mispell, mizelle, moertel, montiel, morelle, morrell, moselle, mozelle, nacelle, niflhel, novelle, novotel, o'shell, oakwell, oilwell, oiselle, oradell, outsell, outwell, ovicell, padelle, panelle, parelle, pedahel, penwell, percell, pesnell, pightel, popwell, poyntel, procell, pucelle, purcell, quesnel, quintel, rachele, railtel, rampell, randell, raphael, rdf/xml, rebelle, reexpel, rephael, respell, revelle, rodwell, romelle, rondell, rosabel, roselle, rouelle, roussel, rozelle, rudelle, samelle, sanibel, sasktel, sawtell, schelle, schmehl, schnell, seawell, sensuel, shantel, sharell, sheftel, shirell, shtetel, shubael, sibelle, sidwell, singtel, sitwell, sofitel, stardel, stokvel, strehle, tarbell, teitell, tigelle, torisel, tugwell, tutelle, twentel, tyrrell, umarell, unspell, unswell, upswell, verdell, vieille, visuell, voyelle, waddell, warrell, well..., zehntel

8 letters:
120-cell, 600-cell, actuelle, aerocele, aisselle, alpharel, amarelle, annabell, archipel, bakewell, bardwell, barnwell, battelle, becknell, beinwell, birdwell, bisexuel, bluebell, bonibell, boscobel, bothwell, boutelle, boutwell, bradwell, bramwell, bretelle, bridwell, brocatel, bromwell, brownell, brunelle, bucknell, by-spell, caffarel, cannelle, cantrell, cantwell, cardwell, carousel, carswell, cashwell, cervelle, chadwell, chanelle, chapelle, cherelle, chevelle, citrucel, claribel, claywell, cockwell, cogswell, coldwell, condotel, cordelle, cornelle, cornwell, coromell, cottrell, cranwell, creswell, crotwell, danielle, dantrell, darrelle, dentelle, desselle, directel, disgavel, doorbell, dowsabel, dumbbell, duracell, edgehtml, eggshell, ellemtel, esquibel, esquivel, estrogel, farewell, flanelle, flexibel, fontanel, footwell, foresail, foretell, fretwell, gabriele, gamewell, get-well, givewell, gladwell, glumelle, godspell, goodsell, gravelle, grinnell, gromwell, hairbell, hardwell, harebell, hartwell, hopewell, hunspell, ikenfell, in-q-tel, intertel, isabelle, keyspell, lacewell, lamellae, laquelle, lasswell, leavelle, leonelle, lilybell, loiselle, longwell, lovewell, lumachel, lyondell, machelle, macintel, manuelle, marcelle, marielle, markwell, martelle, marvelle, materiel, maybelle, michelle, microtel, minicell, misspell, morantel, muscatel, musicxml, nouvelle, nutshell, outdwell, outswell, overhele, oversell, overwell, overzeal, parallel, parlodel, pernelle, petronel, peverell, picocell, pizzelle, polywell, postquel, prunelle, pyrantel, quenelle, querelle, rachelle, ransdell, rochelle, rockwell, rondelle, rothwell, roussell, samuelle, sandwell, sapropel, sarcelle, sardelle, sartwell, sawtelle, schnelle, schwelle, scurdell, sea-mell, seashell, sentelle, seroquel, sewellel, shamelle, shemwell, shirelle, shirrell, shopwell, shortell, shotwell, sidequel, snaefell, sockwell, soldanel, spinelle, stemcell, stepwell, stilwell, storytel, subshell, suchomel, swalwell, tarantel, tourelle, trisquel, turkcell, twaddell, vandaele, variabel, vervelle, verywell, villanel, voicexml, volvelle, wachtell, wardwell, whitesel, whitwell, wombwell

9 letters:
aquarelle, aristotel, bagatelle, bandshell, beta-cell, blackwell, bombshell, bracewell, bracknell, bridewell, broadwell, brockwell, cantrelle, caravelle, carbonell, carrousel, chandelle, chantelle, chappelle, chartwell, che'nelle, chriswell, chylocele, citadelle, clamshell, clientele, cockerell, cocozelle, colpocele, corabelle, courtelle, coverdell, cresselle, cresswell, crosswell, cubanelle, dannielle, easyhotel, ensorcell, femtocell, filoselle, flat-fell, germ-cell, glidewell, greenfell, greenwell, half-cell, hardshell, heartwell, honeywell, horseheal, intercell, intermell, interquel, involucel, kalispell, lactocele, levonelle, mahalalel, marcantel, martorell, materiell, microcell, mirabelle, monostele, moonspell, moschatel, multifuel, naturelle, neuchatel, nifuratel, officetel, organelle, organogel, overswell, pachelbel, parallele, pell-mell, pennywell, personnel, photocell, plausibel, postrelle, prequelle, protocell, quappelle, rivendell, rousselle, rubicelle, sanmiguel, satchwell, self-heal, shantelle, shealtiel, smartcell, snackwell, softshell, southwell, speedwell, stairwell, stillwell, stockwell, supercell, treadwell, trencavel, trenhotel, truesdell, undersell, varicelle, vicontiel, whitesell, zinfandel, zitadelle

10 letters:
accidentel, aiguebelle, balancelle, bartavelle, brightwell, brocatelle, cakchiquel, camberwell, campanelle, cardiocele, carrasquel, christabel, christelle, churchwell, citronelle, clarabelle, coccinelle, commonweal, craniocele, damoiselle, dauerwelle, demoiselle, dinnerbell, dischevele, dreamshell, emmanuelle, fontanelle, francielle, fricadelle, frikadelle, gastrocele, geldbeutel, hirondelle, homosexuel, immortelle, individuel, ischiocele, jargonelle, jarretelle, keratocele, kettlebell, kettlewell, lenticelle, livingwell, medarabtel, motherwell, muscadelle, nerve-cell, neufchatel, orchiocele, overmantel, passerelle, picturetel, pleurocele, protostele, ramatuelle, ritornelle, sauterelle, sentinelle, skaftafell, sltmobitel, spoutshell, tankstelle, tarantelle, think-cell, tinkerbell, unparallel, untertitel, villanelle, willabelle, zwerchfell

11 letters:
additionnel, barbastelle, brackenfell, chantarelle, chanterelle, citronnelle, clerkenwell, fingerspell, fonctionnel, galactocele, groundswell, homosexuell, industriell, jean-michel, jeanmichele, membranelle, nonparallel, pappardelle, pastourelle, pennoncelle, perineocele, pipistrelle, prosocoelle, regenmantel, sickle-cell, spiritielle, spirituelle, subparallel, tagliatelle, tourterelle, waschmittel, zweigstelle

12 letters:
anlegestelle, antiparallel, audiovisuell, casino-hotel, christabelle, conditionnel, elmootazbell, exceptionnel, finger-spell, homosexuelle, industrielle, jean-michele, mademoiselle, pharyngocele, polichinelle, praziquantel, schandmantel, traditionell, traditionnel

13 letters:
anti-materiel, antipersonell, antipersonnel, epigastrocele, heterosexuell, kiss-and-tell, passchendaele, professionnel, schnittstelle, show-and-tell

14 letters:
anti-machiavel, anti-personnel, bushaltestelle, gavel-to-gavel, hypogastrocele, lave-vaisselle, plane-parallel

15 letters:
aix-la-chapelle, aufputschmittel, constitutionnel, sainte-chapelle, wiley-blackwell

16 letters:
meningomyelocele, particle-in-cell, syringomyelocele

17 letters:
mont-saint-michel, regenbogenforelle

18 letters:
domremy-la-pucelle, meurthe-et-moselle