12 letters
- postdeadline19
- postgraduate19
- preadmission20
- preadmitting22
- proofreaders19
- proofreading22
- pseudomonads22
- puzzleheaded39
- quadrangular28
- quadraphonic32
- quadrennials26
- quadrenniums29
- quadricepses29
- quadrillions26
- quadriphonic32
- quadriplegia29
- quadriplegic32
- quadrivalent29
- quadrumanous29
- radicalising20
- radicalizing29
- radiobiology21
- radiocarbons20
- radiochemist21
- radioecology21
- radioelement18
- radiographed21
- radiographic23
- radioisotope16
- radiolabeled19
- radiolarians15
- radiological20
- radiologists16
- radiolucency24
- radiometries16
- radiomimetic22
- radionuclide20
- radiotherapy20
- radiothorium19
- radiotracers16
- railroadings17
- readableness18
- readdressing17
- readjustable27
- readjustment27
- readmissions17
- rebroadcasts19
- reradiations14
- retrogradely18
- retrograding18
- rhodomontade20
- roadblocking27
- roadholdings20
- rodomontades18
- saddlecloths21
- sadistically20
- shadowboxing31
- shadowgraphs25
- shadowgraphy27
- softheadedly22
- spearheading21
- sporadically23
- spreadsheets18
- stadtholders17
- steadinesses14
- sulfadiazine28
- switchblades25
- tarradiddles16
- tetradrachms21
- thunderheads20
- trademarking23
- tradescantia17
- tradespeople20
- traditionary16
- traducements21
- trichomonads22
- ultradistant16
- ultraradical19
- unadvertised20
- unbarricaded22
- unirradiated16
- unnilquadium31
- unsteadiness16
- woodenheaded21