Mammoth Uncensored Word List:
126 words ending with ss, 17 letters long

accommodativeness adventuresomeness argumentativeness authoritativeness bitterheartedness brokenheartedness communicativeness companionableness compassionateness complementariness comprehensiveness conscientiousness consequentialness contemplativeness contradictoriness costeffectiveness demonstrativeness determinativeness directionlessness disadvantagedness disconcertingness dishonourableness disinterestedness dispassionateness disrespectfulness exceptionableness extraordinariness feebleheartedness fickleheartedness fierceheartedness gentleheartedness gentlemanlikeness heterogeneousness hypersensuousness inappropriateness inconceivableness inconsiderateness inconspicuousness indefatigableness indescribableness indeterminateness indispensableness inefficaciousness inexhaustibleness inexpressibleness instantaneousness interpretableness introspectiveness irrecoverableness irreplaceableness irresponsibleness knowledgeableness lightfingeredness miscellaneousness multitudinousness nonconclusiveness nonproductiveness nonreflectiveness nonrefractiveness nonrepetitiveness nonresolvableness nonreversibleness nonseasonableness nonsubmissiveness nonsubversiveness nonsuccessiveness nonsufferableness nonsuggestiveness nonsusceptiveness nonsymbolicalness nontraitorousness nontransitiveness nontumultuousness nontyrannicalness nonvegetativeness nonviviparousness objectionableness overambitiousness overassertiveness overattentiveness overimitativeness overluxuriousness overnegligentness overravishingness overrighteousness oversensitiveness ovoviviparousness perspicaciousness prefigurativeness preternaturalness pusillanimousness reprehensibleness revolutionariness sanctimoniousness semiconsciousness semiobjectiveness semiobliviousness singleheartedness splendiferousness strongheartedness structurelessness supersensuousness superstitiousness superthankfulness supervigilantness supervigorousness surreptitiousness tenderheartedness unaccountableness unadulteratedness unappreciableness unattractableness unauthenticalness unblameworthiness unceremoniousness uncomfortableness uncompetitiveness uncooperativeness unfashionableness unimaginativeness unimpeachableness uninterestingness unpretentiousness unsubstantialness unsynchronousness untrustworthiness