15 letters
- instantaneities18
- instantaneously22
- institutionally22
- instructiveness25
- instructorships25
- instrumentalism25
- instrumentalist22
- instrumentality24
- instrumentation22
- insurrectionist21
- integrationists19
- intellectualist23
- interestingness20
- interlacustrine22
- interscholastic25
- interstratified20
- interstratifies19
- interventionist22
- investigational24
- irrationalistic20
- irresistibility21
- kinesthetically29
- kremlinologists27
- lightfastnesses24
- liturgiologists22
- macrostructural27
- macrostructures26
- magistratically27
- maladministered25
- maldistribution25
- masochistically30
- masterfulnesses24
- mastoidectomies25
- mechanistically31
- medulloblastoma29
- meroblastically29
- metafictionists25
- metalinguistics26
- metastabilities22
- microbiologists27
- microstructural27
- microstructures26
- misconstruction27
- misdistribution24
- misregistration21
- mistranscribing28
- mistranslations21
- mistrustfulness25
- monocrystalline27
- monstrousnesses21
- multilateralist22
- neocolonialists22
- neuroanatomists21
- neurobiologists23
- neuroblastomata24
- neuroscientists21
- nonantagonistic24
- nonaristocratic23
- nonastronomical25
- noncombustibles31
- nonconstruction26
- nonconstructive29
- noninstrumental24
- nonobjectivists36
- nonpsychiatrist27
- nonrelativistic25
- nonstationaries18
- notwithstanding26
- obstinatenesses20
- obstructionisms26
- obstructionists23
- obstructiveness27
- operationalists20
- ophthalmologist29
- orchestrational22
- osteomyelitides22
- osteopathically27
- overabstracting28
- overadjustments34
- overconstructed28
- overestimations23
- overinvestments28
- overorchestrate24
- overstabilities23
- overstimulating27
- overstimulation25
- paleobiologists25
- paleoecologists25
- paleomagnetists25
- paleontologists23
- paleozoologists31
- pantheistically28
- pantisocratists22
- paralinguistics26
- parasitologists21
- particularistic26
- pasteurizations29
- pectinesterases22
- perfectionistic28
- pessimistically28
- pestiferousness23
- pharmacognostic32
- pharmacologists29
- phenomenalistic29
- phenomenologist28
- philanthropists27
- photobiologists26
- photogeologists25
- photojournalist32
- physiotherapist27
- plasticizations32
- pluralistically28
- polycrystalline29
- postadolescents24
- postapocalyptic33
- postconsonantal25
- postdevaluation26
- postdivestiture24
- posthemorrhagic30
- postinoculation25
- postirradiation20
- postmasterships26
- postmillenarian25
- postoperatively28
- postpollination25
- postproductions27
- poststimulation24
- poststimulatory25
- posttransfusion24
- postvaccination30
- predestinarians21
- predestinations21
- preestablishing27
- preformationist25
- prehistorically27
- preregistration21
- prerevisionists23
- preservationist23
- prestidigitator21
- prestigiousness22
- procrastinating25
- procrastination23
- procrastinators22
- prognosticating27
- prognostication25
- prognosticative28
- prognosticators24
- progressivistic27
- prohibitionists24
- prostatectomies24
- prosthodontists22
- protohistorians21
- protozoologists30
- pseudoscientist24
- psychoacoustics32
- psychobiologist31
- psychohistorian28
- psychohistories27
- psycholinguists30
- psychophysicist35
- psychotherapist30
- quarterfinalist30
- radiobiologists22
- radiostrontiums21
- radiotherapists21
- reafforestation22
- reconstitutions21
- reconstructible27
- reconstructions24
- recrystallizing34
- redistillations19
- redistributions21
- reestablishment25
- reindustrialize28
- reinstallations19
- reinvestigating25
- reinvestigation23
- remonstratively26
- reorchestrating23
- reorchestration21
- repristinations20
- repudiationists21
- reregistrations18
- reservationists20
- resistibilities19
- resistivenesses20
- restrengthening24
- restrictionisms22
- restrictionists19
- restrictiveness23
- resurrectionist20
- resystematizing32
- retinoblastomas23
- rheumatologists24
- ritualistically24
- roentgenologist22
- rumbustiousness25
- sacramentalists23
- sadomasochistic27
- schistosomiases23