Mammoth Uncensored Word List:
80 words ending with an, 13 letters long

aircraftwoman alongshoreman alphabetarian antichristian antiquitarian anythingarian archipelagian arithmetician assemblywoman authoritarian backswordsman bildungsroman businesswoman callithumpian cliometrician coastguardman communitarian congresswoman cybernetician diagnostician documentarian dosimetrician draughtswoman encyclopedian entomostracan euphausiacean foraminiferan geopolitician handcraftsman hippopotamian hyperphrygian ichthyopsidan iguanodontian inegalitarian informatician lighthouseman linguistician lowerclassman machiavellian malacostracan mastigophoran mathematician megalopolitan megalosaurian metaphysician necessitarian neogrammarian nightwatchman nonequestrian nonpolitician nonvegetarian numismatician ornithischian paediatrician peptidoglycan phalansterian phantasmalian platyrrhinian plesiosaurian polyhistorian postlapsarian premillennian privateersman proglottidean propraetorian quartodeciman rhizocephalan scintilliscan stagecoachman suburbicarian supersalesman systematician technopolitan terpsichorean tobaccanalian transisthmian underclassman upperclassman valedictorian woodcraftsman