Mammoth Uncensored Word List:
124 - 17 letter words starting with s

saccharifications salpingostomatomy sanctimoniousness saponaceousnesses scandalmongerings scapuloclavicular schizophrenically scintigraphically scintimammography semiautomatically semiconsciousness semidocumentaries semidomestication semiobjectiveness semiobliviousness semipornographies semiprofessionals sententiousnesses septendecilliards septendecillionth septingentillions septuagintilliard septuagintillions serviceablenesses sesquicentenaries sesquicentennials sesquipedalophobe sestrigintillions sesvigintillionth sexagintilliardth sexagintillionths siderodromophobes siderodromophobia siderodromophobic silicoflagellates singleheartedness socioeconomically softheartednesses spectroheliograms spectroheliograph spectrohelioscope spectrophotometer spectrophotometry spectroradiometer spectroscopically sphingoglycolipid sphygmomanometers sphygmomanometric spiritualizations splanchnoskeletal splanchnoskeleton splendiferousness spondylolisthesis spontaneousnesses standoffishnesses staphylorrhaphies stereochemistries stereolithography stereomicroscopes stereomicroscopic stereophotography stereoselectively stereoselectivity stereospecificity straightforwardly straightjacketing straitlacednesses stratigraphically stratospherically strongheartedness strongyloidosises structuralization structurelessness subcategorization subclassification subconfigurations subjectivizations subordinatenesses subrepresentation substantialnesses substantivenesses superbillionaires supercivilization superconductivity superconglomerate superconservative supercorporations superefficiencies superfecundations superfluousnesses superheavyweights superintellectual superintelligence superintendencies superlativenesses supermillionaires superminicomputer supernaturalistic superplasticities superregenerative superromantically superromanticisms supersensualistic supersensuousness superspecializing superspectaculars superspeculations superstimulations superstitiousness superthankfulness supervigilantness supervigorousness suppressibilities suppressivenesses supranationalisms supranationalists surreptitiousness susceptiblenesses suspensefulnesses swellheadednesses symmetricalnesses symptomatological synchrocyclotrons synchronousnesses