4 letters:
corm, dorm, form, norm, orme, warm

5 letters:
-form, dorme, enorm, forme, horme, norme, scorm, slorm, storm, swarm, torme, xform

6 letters:
aswarm, biform, deform, efform, enform, enorme, inform, reform, rewarm, t-norm, unform, unwarm

7 letters:
aciform, aliform, ausform, bestorm, by-form, conform, deforme, deiform, difform, informe, isoform, jotform, lauwarm, misform, oriform, outform, oviform, perform, pliform, preform, proform, re-form, schwarm, t-storm, triform, uniform, upswarm, webform

8 letters:
acneform, aeriform, age norm, alestorm, ansiform, aquiform, arciform, arkstorm, art form, auriform, benidorm, boniform, boviform, ciliform, cineform, coliform, conforme, coniform, cubiform, cuniform, difforme, ensiform, equiform, fabiform, feliform, ficiform, filiform, flexform, freeform, funiform, fusiform, gasiform, geostorm, gruiform, haloform, hamiform, homiform, iodoform, janiform, juliform, kaliform, landform, lifeform, luciform, lukewarm, luniform, lupiform, lyriform, maniform, moriform, muciform, muriform, napiform, nariform, nasiform, natiform, nuciform, omniform, outstorm, paliform, pediform, perform', phpstorm, piliform, piniform, piriform, pisiform, planform, platform, poriform, pro-form, puriform, pyriform, rabiform, ramiform, raniform, raystorm, remiform, reniform, retiform, riziform, rotiform, rubiform, semiform, seminorm, setiform, slipform, soliform, sudiform, tax form, theiform, tubeform, tubiform, unciform, uncoform, uniforme, ursiform, utriform, variform, vasiform, veriform, waveform

9 letters:
aciniform, acneiform, adeniform, anguiform, axiniform, bacciform, barnstorm, blogswarm, bromoform, bulbiform, bulliform, bursiform, cactiform, cairngorm, calciform, capriform, cauliform, celliform, cheliform, chyliform, ciliiform, cirriform, claviform, colliform, cominform, cordiform, cordoform, corniform, costiform, cteniform, cuneiform, curviform, cymbiform, dentiform, disciform, disinform, dolioform, duststorm, eruciform, falciform, fibriform, filiforme, firestorm, floriform, foveiform, free form, fundiform, fungiform, galeiform, galliform, gemmiform, graniform, guttiform, hailstorm, halestorm, hydriform, ice storm, inconform, lanciform, landstorm, larviform, leaf form, lentiform, leptiform, libriform, life form, ligniform, lindiform, lituiform, maelstorm, mammiform, microform, misinform, misreform, mitriform, montiform, multiform, mummiform, musciform, myrtiform, nautiform, nitroform, nummiform, oculiform, ovaliform, palpiform, pappiform, peltiform, penniform, perciform, pileiform, pinniform, pisciform, planiform, plattform, plexiform, pre-storm, rainstorm, ralliform, restiform, ruiniform, sacciform, salpiform, sandstorm, scapiform, scobiform, scopiform, scoriform, scutiform, selliform, septiform, serriform, snowstorm, soleiform, spiciform, spiniform, stipiform, styliform, sulciform, take form, tauriform, tectiform, terraform, transform, turdiform, unciforme, unconform, unguiform, urceiform, valviform, vergiform, vermiform, villiform, vitriform, vulviform, wave form, whereform, wildstorm, windstorm, word form

10 letters:
actiniform, aculeiform, amentiform, amoebiform, anginiform, anseriform, araneiform, arboriform, ascidiform, baculiform, bloodstorm, botuliform, bound form, brainstorm, brianstorm, bufoniform, calceiform, calyciform, cancriform, caniniform, chloroform, choreiform, claim form, clypeiform, conchiform, coroniform, coryneform, cotyliform, cribriform, cruciforme, cuculiform, cucumiform, cultriform, cumuliform, cupuliform, cyathiform, dendriform, digitiform, disuniform, dust-storm, dust storm, elytriform, emboliform, etheriform, filariform, fluoroform, funiliform, funnelform, gangliform, gastronorm, ginglyform, glandiform, humaniform, hydatiform, lageniform, letterform, lightstorm, limaciform, line storm, linguiform, maidenform, malleiform, medusiform, molariform, monadiform, moniliform, motorstorm, noisestorm, nonuniform, nucleiform, obpyriform, order form, ostreiform, outperform, overinform, pateriform, petaliform, phylliform, poculiform, polypiform, preconform, proteiform, pumiciform, punctiform, quadriform, racemiform, radiciform, raduliform, resiniform, rostriform, saliniform, salverform, samariform, scrotiform, scyphiform, securiform, somatoform, spathiform, spongiform, springform, squaliform, squamiform, stelliform, stilliform, stratiform, strigiform, strumiform, subuliform, tabetiform, technivorm, tetaniform, thermoform, tubuliform, umbiliform, vaporiform, variciform, verse form, ypsiliform

11 letters:
aciculiform, acinaciform, acinetiform, aluminiform, alveoliform, ampulliform, andrew form, antenniform, antheriform, asbestiform, bacilliform, basaltiform, blamestrorm, branchiform, bulletstorm, calathiform, calcariform, campaniform, capilliform, castlestorm, cerebriform, chancriform, change form, chloroforme, choleriform, columbiform, columniform, coraciiform, coralliform, corticiform, corymbiform, crateriform, cypriniform, cypseliform, diversiform, dolabriform, drepaniform, electroform, falconiform, fistuliform, ganglioform, granitiform, granuliform, harengiform, herpetiform, isopodiform, kidney-form, lamelliform, land-reform, land reform, laniariform, licheniform, mamilliform, maxilliform, metalliform, muscariform, overperform, ovopyriform, pampiniform, panduriform, papilliform, passeriform, patelliform, pectiniform, plumiliform, plural form, pustuliform, radiatiform, retransform, sagittiform, sandaliform, scalariform, scalpriform, scombriform, siliqyiform, sonata form, spiculiform, stipitiform, subpyriform, trapeziform, umbelliform, vacciniform, varioliform, verruciform, z-transform, zeolitiform, zosteriform

12 letters:
amianthiform, amygdaliform, anguilliform, beeldenstorm, cocleariform, cylindriform, ectocuniform, embryoniform, entocuniform, epileptiform, equisetiform, extractiform, fibrilliform, flabelliform, flagelliform, fungilliform, gelatiniform, hydatidiform, lachrymiform, lebensreform, lumbriciform, mammilliform, membraniform, mesocuniform, meteor swarm, morbilliform, neuralgiform, operculiform, paraboliform, pelecaniform, placentiform, plataleiform, psittaciform, rostelliform, scutelliform, serpentiform, silver storm, stalactiform, stalactoform, strobiliform, thunderstorm, underperform, vesiculiform

13 letters:
acetabuliform, adipoceriform, ambulacriform, apoplectiform, campaniliform, citation form, cochleariform, columelliform, crossplatform, dress uniform, entocuneiform, hyperboliform, madreporiform, mandibuliform, mesocuneiform, multiplatform, penicilliform, semipenniform, singular form, strombuliform, tentaculiform, trichiuriform, umbraculiform, varicelliform, violent storm

14 letters:
aspergilliform, combining form, cross-platform, electric storm, hippocrepiform, labyrinthiform, magnetic storm, multi-platform, proboscidiform, salamandriform, scarlatiniform, space platform, stalactitiform, telegraph form

15 letters:
cook up a storm, hypocrateriform, infundibuliform, nitrochloroform, puzzle-platform, terebratuliform

16 letters:
application form, electrical storm, military uniform, nitro-chloroform, schizophreniform, weapons platform

17 letters:
drilling platform

18 letters:
political platform

19 letters:
heroes of the storm

21 letters:
google cloud platform

22 letters:
operation desert storm