Mammoth Uncensored Word List:
70 words ending with is, 15 letters long

achillobursitis achondrogenesis adenohypophysis agranulocytosis ancylostomiasis ankylostomiasis anthropogenesis antiperistalsis ariboflavinosis atherosclerosis balanoposthitis chorioallantois costochondritis dermatomyositis dermatophytosis diaphragmatitis electroanalysis electrodialysis electrophoresis enterohepatitis erythrocyanosis ferrocalcinosis fusospirillosis gastroenteritis gluconeogenesis glyconeogenesis hemangiogenesis hemangiomatosis hemochromatosis hepatocirrhosis hepatolithiasis hypochondriasis hypodermoclysis immunodiagnosis leukaemogenesis macrometastasis monocytopoiesis nasopharyngitis nephrolithiasis nephrosclerosis neurodermatitis neurohypophysis nucleosynthesis onychocryptosis osteochondritis osteochondrosis pachymeningitis panophthalmitis parthenogenesis pharyngoxerosis phlebolithiasis phlebosclerosis phytodermatitis pneumosilicosis pseudoarthrosis pseudoparalysis psychosynthesis pycnodysostosis pyknodysostosis rhinotracheitis schistosomiasis sclerokeratitis spermatogenesis steatohepatitis steroidogenesis strongyloidosis theriomorphosis thoracocentesis thromboangiitis trypanosomiasis