13 letters
- kapellmeister25
- laryngoscopes25
- micropipettes25
- misperceiving29
- misperception26
- multispectral25
- neuropeptides22
- nincompoopery29
- nonappearance25
- noncompetitor24
- noncooperator21
- nondependents22
- nondispersive23
- nonexpendable31
- nonhappenings27
- nonperformers24
- nonperforming27
- nonperishable24
- nonpermissive25
- nonpersistent19
- nonpetroleums23
- nonspecialist22
- omnicompetent27
- openabilities21
- openheartedly23
- openmouthedly27
- operabilities20
- operationally21
- operationisms20
- operationists17
- operativeness21
- operosenesses17
- oscilloscopes24
- outperforming26
- overdependent24
- overdeveloped27
- overoperating23
- overpedalling26
- overpersuaded23
- overpersuades22
- overspeculate25
- pancytopenias26
- panleukopenia27
- paperhangings27
- peaceableness24
- peacekeepings29
- pearlescences24
- peculiarities21
- pedagogically28
- pedestrianism21
- pediatricians21
- peevishnesses23
- pelletization28
- penalizations28
- pendulousness22
- penetrability23
- penetratingly23
- penetrometers20
- penicillamine26
- penicillinase23
- penitentially22
- pennywhistles26
- pensivenesses22
- pentapeptides24
- pentaploidies22
- pentobarbital24
- penultimately25
- penuriousness20
- peppergrasses24
- pepperinesses23
- peptidoglycan29
- peradventures23
- perambulating27
- perambulation25
- perambulators24
- perambulatory26
- percussionist21
- perdurability24
- peregrinating22
- peregrination20
- perfectionism26
- perfectionist23
- perfectnesses23
- performatives26
- perfunctorily27
- perfusionists21
- perichondrium27
- periodicities20
- periodization27
- periodontally22
- periodontists18
- periostitises16
- perishability24
- perissodactyl23
- peritonitises17
- permanentness22
- permanganates23
- permutational22
- perpendicular26
- perpetrations20
- perpetuations21
- perphenazines32
- perseverances24
- perseverating23
- perseveration21
- perseveringly26
- persistencies20
- personalising21
- personalistic21
- personalities18
- personalizing30
- perspectively29
- perspicacious26
- perspicuities23
- perspicuously27
- perspirations20
- pertinacities20
- perturbations21
- pervasiveness25
- pervertedness22
- pestiferously23
- petrifactions23
- petrification23
- petrochemical28
- petrographers23
- petrographies23
- pettifoggings26
- pettishnesses19
- pharmacopeial28
- pharmacopeias27
- photoperiodic25
- postoperative23
- preexperiment30
- prespecifying30
- prospectively29
- pteridosperms23
- pumpernickels32
- quasiperiodic30
- radioisotopes17
- reappearances23
- recuperations21
- reexperienced28
- reexperiences27
- reinspections21
- repeatability22
- repercussions21
- repetitiously20
- retrospecting22
- retrospection20
- retrospective23
- scapegoatings24
- scapegoatisms24
- semipermanent24
- semipermeable26
- sesquiterpene27
- shapelessness20
- shapelinesses20
- sharecroppers24
- speakerphones26
- specialnesses21
- specification26
- specificities25
- spectacularly27
- spectatorship24
- spectinomycin29
- spectrographs26
- spectrography28
- spectrometers22
- spectrometric25
- spectroscopes25
- spectroscopic28
- specularities21
- speculatively28
- speechwriters24
- speedboatings23
- speleological24
- speleologists20
- spermatocytes24
- spermatogenic25
- spermatogonia22
- spermatophore24
- spermatophyte26
- spermatozoans29
- spermatozoids29
- spokespersons24
- stipendiaries18
- stupefactions24
- subspecialist24
- subspecialize33
- superableness22
- superabounded24
- superabundant24
- superachiever26
- superactivity26
- superaddition20
- superagencies23
- superannuated21
- superannuates20
- superathletes20
- supercabinets24