Mammoth Uncensored Word List:
26 words that are 20 letters long beginning with a in the mammoth uncensored word list.

abdominohysterectomy abetalipoproteinemia acetylcholinesterase acetylmethylcarbinol adrenocorticosteroid adrenocorticotrophic adrenocorticotrophin adrenocorticotropins adrenoleukodystrophy anatomicophysiologic anthropocentricities anthropomorphization antiauthoritarianism anticonservationists antienvironmentalism antienvironmentalist antifluoridationists antiinstitutionalist antiinsurrectionally antiinsurrectionists antiparliamentarians archaeometallurgical arthroophthalmopathy autolithographically autoradiographically autotransplantations