Mammoth Uncensored Word List:
137 words ending with an, 12 letters long

aesthetician ambulanceman antediluvian antemeridian archdiocesan archosaurian artilleryman baccalaurean bacchanalian backcourtman backswordman backwoodsman ballistician biometrician cancellarian cantharidian carragheenan catilinarian celibatarian cephalopodan chondrostian cochairwoman committeeman consistorian cosmopolitan councilwoman countrywoman crassulacean cryptogamian deepwaterman dialectician dibenzofuran dictyopteran diprionidian discomedusan doctrinarian dodecagynian ephemeridian episcopalian epistolarian equalitarian footplateman frontiersman frontomedian fustillirian futilitarian geometrician geriatrician gladiatorian hereditarian heterokontan heteroousian heteropteran hippocrepian humanitarian hydromedusan hymenopteran hypophrygian labyrinthian laundrywoman lepidopteran longshoreman machiavelian majoritarian marsupialian mesoamerican metropolitan monodelphian newspaperman nonagenarian noneuclidean nonlibrarian nonmammalian nonmendelian nonphysician nonsectarian nothingarian obstetrician octogenarian odontophoran onomastician onychophoran osteichthyan paradoxidian parkinsonian pediatrician pentapolitan phytozoarian pogonophoran postdiluvian postmeridian prehistorian prelapsarian presbyterian proboscidean proboscidian procellarian proteoglycan prototherian pterosaurian salamandrian saltpetreman salutatorian scandinavian semeiotician servicewoman sexagenarian slaughterman spermatozoan statistician stegosaurian sublapsarian sublibrarian subterranean syntactician tauromachian teleosaurian tetrapolitan theoretician totalitarian transleithan transuranian trichopteran trustafarian turbellarian ubiquitarian vaudevillean vaudevillian velocipedean velocipedian ventromedian vespertilian veterinarian vicechairman vocabularian warehouseman workingwoman