Mammoth Uncensored Word List:
115 - 9 letter words starting with is

isabellas isagogics isallobar isarithms ischaemia ischaemic ischemias ischiadic ischiatic ischurias iseikonia iseikonic isenergic isinglass islanders islanding islomania ismatical isobarism isobathic isobronts isobutane isobutene isobutyls isobutyne isochasms isocheims isochimal isochimes isochores isochoric isochrone isochrons isochrony isoclinal isoclines isoclinic isocratic isocrymal isocrymes isocyanic isocyclic isodecane isodecene isodecyne isodisomy isodomons isodomous isodontal isoenzyme isogamete isogamies isogamous isogeneic isogenies isogenous isogonals isogonics isogonies isografts isographs isohexane isohexene isohexyne isohydric isohyetal isokontan isolating isolation isolative isolators isologous isologues isomerase isomerise isomerism isomerize isomerous isometric isomorphs isoniazid isonomies isonomous isononane isononene isononyne isooctane isooctene isooctyne isophones isophotal isophotes isopleths isopodans isopodous isopolity isoprenes isopropyl isopycnal isopycnic isosceles isosmotic isostatic isosteric isotactic isotheral isotheres isotherms isotopies isotropic ispaghula issuances issueless isthmians isthmuses