Mammoth Uncensored Word List:
21 - 16 letter words starting with au

auspiciousnesses authoritarianism autobiographical autocorrelations autodecrementing autodidactically autoimmunization autoincrementing autointoxication autolithographer autolithographic automanipulation automanipulative automatonophobes automatonophobia automatonophobic autopolyploidies autoradiographer autoradiographic autotransformers autotransfusions