Mammoth Uncensored Word List:
77 - 17 letter words starting with o

objectionableness obstructivenesses oceanographically octingentillionth octodecilliardths octogintilliardth octogintillionths octopentagesimals octotrigintillion octovigintillions oculodentodigital odoriferousnesses oligoastrocytomas oligodendroglioma onomatopoetically openheartednesses openmouthednesses operationalisable operationalizable opinionatednesses opportunistically opprobriousnesses organophosphorous organotrophically orthogeosynclinal orthogeosynclines orthogonalization orthopsychiatries orthopsychiatrist oscilloscopically otolaryngological otolaryngologists overambitiousness overassertiveness overattentiveness overcommercialize overcommunicating overcommunication overcompensations overconcentration overconscientious overdetermination overembellishment overexaggerations overexploitations overextrapolation overfamiliarities overfertilization overimaginatively overimitativeness overindustrialise overindustrialism overindustrialize overluxuriousness overmagnification overnegligentness overorchestrating overpreoccupation overprescriptions overpresumptively overprocrastinate overproportionate overproportioning overqualification overrationalizing overravishingness overrighteousness oversensitiveness oversensitivities oversophisticated overspeculatively oversubscriptions oversuperstitious overurbanisations overurbanizations overzealousnesses ovoviviparousness