14 letters
- indecomposable29
- indemonstrable24
- indestructible24
- indeterminable24
- indiscoverable27
- indispensables24
- inevitableness24
- inexorableness27
- inflectionally27
- inflexibleness31
- inimitableness23
- insatiableness20
- insensibleness21
- insuppressible26
- insurmountable25
- intangibleness23
- intellectively27
- intellectually25
- interdialectal21
- interelectrode20
- intermolecular24
- internucleonic25
- intolerability22
- intolerantness18
- intramolecular24
- invaluableness26
- invincibleness28
- inviolableness25
- irreconcilable26
- irreproachable26
- irreproducible26
- irresponsibles22
- knuckleballers33
- lamentableness24
- landlessnesses19
- laudablenesses22
- leachabilities24
- legalistically25
- legislatorship23
- legitimatizing32
- legitimization30
- lepidopterists22
- letterspacings24
- leukemogeneses26
- leukemogenesis26
- leukodystrophy30
- lexicalisation27
- lexicalization36
- lexicographers32
- lexicographies32
- lifelessnesses20
- listlessnesses17
- lovelessnesses21
- macromolecular29
- macromolecules29
- macronucleuses27
- malleabilities23
- manageableness25
- meddlesomeness24
- mesdemoiselles23
- metronidazoles29
- microelectrode25
- micronucleuses27
- microparticles27
- millenarianism24
- millennialisms25
- millennialists22
- mindlessnesses21
- monocotyledons26
- mononucleotide25
- motherlessness21
- motionlessness20
- movelessnesses23
- muddleheadedly28
- multidialectal25
- multielectrode24
- multimolecular28
- multinucleated26
- myelencephalic33
- myelencephalon31
- namelessnesses20
- needlessnesses18
- neglectfulness27
- newfangledness27
- nonaccountable28
- noncelebration24
- noncelebrities23
- noncombustible30
- noncondensable26
- nonconvertible28
- nondegradables24
- nonelectrolyte23
- nonelectronics24
- nonequivalence35
- nonequivalents32
- nonfissionable24
- nonforfeitable26
- noninflammable31
- nonjusticiable33
- nonperishables25
- nonpolarizable33
- nonrecyclables29
- nonreturnables22
- nucleoproteins24
- objectlessness31
- obsoletenesses19
- oleaginousness20
- oleomargarines21
- optoelectronic25
- orthomolecular25
- overcontrolled25
- overlengthened26
- overprivileged29
- painlessnesses20
- paleobiologies24
- paleobiologist24
- paleobotanical26
- paleobotanists22
- paleoecologies24
- paleoecologist24
- paleogeography29
- paleographical29
- paleomagnetism27
- paleomagnetist24
- paleontologies22
- paleontologist22
- paleopathology28
- paleozoologies30
- paleozoologist30
- palletizations29
- pamphleteering29
- panleukopenias28
- parallelepiped27
- parallelograms25
- pardonableness24
- particleboards25
- pathlessnesses21
- pelletizations29
- personableness23
- pestilentially23
- phenylephrines29
- philhellenisms28
- philhellenists25
- phlebographies30
- phlegmatically32
- photoelectrons24
- pinealectomies25
- pinealectomize34
- pitiablenesses22
- pitilessnesses19
- planlessnesses21
- pleasantnesses20
- pleasingnesses22
- pleasurability25
- pleonastically26
- plethysmograms30
- plethysmograph32
- plotlessnesses20
- polynucleotide27
- polypropylenes30
- possessionless19
- postadolescent23
- postcollegiate24
- postmillennial25
- preadolescence26
- preadolescents23
- premillenarian24
- presettlements22
- pretensionless20
- profitableness25
- proletarianise19
- proletarianize28
- proportionable25
- provablenesses26
- psychobabblers34
- quasiparticles31
- radiotelegraph23
- radiotelemetry21
- radiotelephone22
- radiotelephony24
- rationalizable29
- reaccelerating24
- readablenesses20
- reasonableness20
- recklessnesses23
- reconcilements26
- reconfigurable28
- rediscountable24
- reflectiveness26
- reflectivities25
- reflectometers24
- reflectorizing33
- regardlessness19
- relentlessness18
- reliablenesses20
- remarkableness26
- replenishments25
- reprogrammable29
- resistlessness16
- resplendencies24