There are 417 fourteen-letter words containing A, F, N and S, https://www.bestwordlist.com/c/a/4/14letterwordswithafns.htm
ABORTIFACIENTS ABSORBEFACIENT ACETIFICATIONS ACIDIFICATIONS AFFECTEDNESSES
AFFECTLESSNESS AFFENPINSCHERS AFFLUENTNESSES AFFORESTATIONS AFFREIGHTMENTS
AFTERSENSATION AIRCRAFTSWOMAN AIRCRAFTSWOMEN AMPLIFICATIONS ANGUSTIFOLIATE
ANTIFEDERALIST ANTIFILIBUSTER ANTIFOREIGNERS ANTIFORMALISMS ANTIFORMALISTS
ANTISCIENTIFIC ARTIFICIALNESS AUTOINFECTIONS BEATIFICATIONS BENEFACTRESSES
BENEFICIALNESS BENEFICIATIONS BIOINFORMATICS BLAMEFULNESSES BLANKETFLOWERS
BOASTFULNESSES BRASSFOUNDINGS BREASTFEEDINGS CALCIFICATIONS CANDLESNUFFERS
CAPRIFICATIONS CAREFREENESSES CARNIFICATIONS CENTRIFUGALISE CERTIFICATIONS
CHIEFTAINESSES CHIEFTAINSHIPS CHYLIFICATIONS CHYMIFICATIONS CIPROFLOXACINS
CLARIFICATIONS CLASSIFICATION COALIFICATIONS COLOURFASTNESS CONFABULATIONS
CONFARREATIONS CONFEDERATIONS CONFESSIONALLY CONFIGURATIONS CONFLAGRATIONS
CONFRONTATIONS CONTRAFAGOTTOS CORNIFICATIONS COTRANSFERRING CRAFTSMANSHIPS
CYCLOPARAFFINS DAMNIFICATIONS DANDIFICATIONS DEFEASIBLENESS DEFEMINISATION
DEFENESTRATING DEFENESTRATION DEFIBRINATIONS DEFINABILITIES DEFORESTATIONS
DELIRIFACIENTS DENSIFICATIONS DESULFURATIONS DIAMANTIFEROUS DIAMONDIFEROUS
DIEFFENBACHIAS DIFFARREATIONS DIFFERENTIATES DIGNIFICATIONS DISAFFILIATING
DISAFFILIATION DISAFFIRMANCES DISAFFIRMATION DISAFFORESTING DISCONFORMABLE
DISDAINFULNESS DISENFRANCHISE DISFEATUREMENT DISFIGURATIONS DISFORESTATION
DISFRANCHISING DISINFESTATION DISINFORMATION DISYLLABIFYING DRAFTSMANSHIPS
DREADFULNESSES DREAMFULNESSES DULCIFICATIONS DWARFISHNESSES EFFEMINATENESS
EMULSIFICATION ESTERIFICATION EXTRAFORANEOUS FABULOUSNESSES FACELESSNESSES
FACINOROUSNESS FACTIONALISING FACTIOUSNESSES FACTITIOUSNESS FACTORISATIONS
FACTORIZATIONS FAINTISHNESSES FAITHFULNESSES FALLACIOUSNESS FALLIBLENESSES
FALSIFICATIONS FAMILIARNESSES FANATICISATION FANCIFULNESSES FANTASTICALITY
FANTASTICATING FANTASTICATION FARCICALNESSES FARFETCHEDNESS FARSIGHTEDNESS
FARTHINGSWORTH FASCICULATIONS FASHIONABILITY FASHIONMONGERS FASHIONMONGING
FASHIOUSNESSES FASTIDIOUSNESS FATHERLESSNESS FATHERLINESSES FATHOMLESSNESS
FATIGUABLENESS FAVOURABLENESS FAVOUREDNESSES FEARLESSNESSES FEARMONGERINGS
FEARSOMENESSES FEASIBLENESSES FEATHERINESSES FEDERALISATION FERRICYANOGENS
FERRIMAGNETISM FERROCYANOGENS FERROMAGNESIAN FERROMAGNETISM FERROMANGANESE
FERTILISATIONS FERTILIZATIONS FETISHISATIONS FETISHIZATIONS FEUDALISATIONS
FEUDALIZATIONS FICTIONALISING FICTIONALITIES FICTIONISATION FIGURATIVENESS
FILTERABLENESS FINEABLENESSES FINGERBREADTHS FISSIONABILITY FLABBERGASTING
FLAGELLANTISMS FLAGELLOMANIAS FLAGITIOUSNESS FLAGRANTNESSES FLAVOPURPURINS
FLAWLESSNESSES FLEXITARIANISM FLIPPANTNESSES FLOCCILLATIONS FLUNITRAZEPAMS
FONCTIONNAIRES FORAMINIFERANS FORAMINIFEROUS FOREHANDEDNESS FORESHADOWINGS
FORESTALLMENTS FORMALISATIONS FORMALIZATIONS FORMIDABLENESS FORNICATRESSES
FORSAKENNESSES FORTIFICATIONS FOSSILISATIONS FOSSILIZATIONS FOUNDATIONLESS
FOURSQUARENESS FRACTIONALISED FRACTIONALISES FRACTIONALISMS FRACTIONALISTS
FRACTIONALIZES FRACTIONATIONS FRAGMENTATIONS FRAGRANTNESSES FRANCHISEMENTS
FRANGIBILITIES FRATERNISATION FRAUDULENTNESS FREAKISHNESSES FREEHANDEDNESS
FREQUENTATIONS FREQUENTATIVES FRINGILLACEOUS FRONTIERSWOMAN FRUITARIANISMS
FUNAMBULATIONS FUNCTIONALISMS FUNCTIONALISTS FUNDAMENTALISM FUNDAMENTALIST
GEMEINSCHAFTEN GESELLSCHAFTEN GLANDULIFEROUS GLORIFICATIONS GRACEFULNESSES
GRATEFULNESSES GRATIFICATIONS HALFWITTEDNESS HANDICRAFTSMAN HANDICRAFTSMEN
HORRIFICATIONS IMPERFORATIONS INEFFABILITIES INEFFICACITIES INFALLIBILISMS
INFALLIBILISTS INFALLIBLENESS INFAMOUSNESSES INFEASIBLENESS INFINITESIMALS
INFLATEDNESSES INFORMATICIANS INFRALAPSARIAN INFRAPOSITIONS INFRASTRUCTURE
INSIGNIFICANCE INSIGNIFICANCY INTERFEROGRAMS JELLIFICATIONS JOLLIFICATIONS
JUSTIFICATIONS KARSTIFICATION LABEFACTATIONS LEAFLESSNESSES LIGNIFICATIONS
LIGNOSULFONATE LITHIFICATIONS LOATHFULNESSES MAGNIFICATIONS MANIFESTATIONS
MANIFESTNESSES MANIFOLDNESSES MANUFACTURINGS MASSIFICATIONS MEANINGFULNESS
MELLIFICATIONS METAFICTIONIST METRIFICATIONS MICROFILAMENTS MISCLASSIFYING
MISINFORMATION MODIFIABLENESS MOLLIFICATIONS MORTIFICATIONS MULTIFILAMENTS
MUMMIFICATIONS MUNDIFICATIONS MUNDIFICATIVES MYSTIFICATIONS NEUROFEEDBACKS
NEWFANGLEDNESS NITRIFICATIONS NITROPARAFFINS NONCLASSIFIEDS NONFILAMENTOUS
NONFISSIONABLE NONSIGNIFICANT NULLIFICATIONS OPSONIFICATION OUTFANGTHIEVES
OVERINFLATIONS PALMIFICATIONS PARAINFLUENZAS PASSIONFLOWERS PEACEFULNESSES
PERFECTIONATES PETRIFICATIONS PLEBIFICATIONS PONTIFICATIONS PORNIFICATIONS
PREFERABLENESS PREFIGURATIONS PRESANCTIFYING PROFESSIONALLY PROFITABLENESS
PROLIFERATIONS PROLIFICATIONS PUTRIFICATIONS QUALIFICATIONS QUINQUEFARIOUS
REAFFIRMATIONS RECTIFICATIONS REFASHIONMENTS REFOCILLATIONS REFORESTATIONS
REFORMATIONIST REFORMULATIONS REFRACTIVENESS REFRACTORINESS REFRIGERATIONS
REINFESTATIONS REMANUFACTURES RESINIFICATION RETRANSFERRING RETRANSFORMING
REUNIFICATIONS SANCTIFICATION SANGUIFICATION SAPONIFICATION SCARIFICATIONS
SCHADENFREUDES SCIENTIFICALLY SCORIFICATIONS SELFSAMENESSES SHAMEFACEDNESS
SHAMEFULNESSES SHAPESHIFTINGS SHRINKFLATIONS SIGNIFICANCIES SIGNIFICATIONS
SILICIFICATION SIMPLIFICATION SOFTHEADEDNESS SOLIDIFICATION SOLIFIDIANISMS
SPAGHETTIFYING SPECIFICATIONS SPIFFLICATIONS SPORTFISHERMAN STAGFLATIONARY
STEDFASTNESSES STOMACHFULNESS STRATIFICATION STULTIFICATION SUBCLASSIFYING
SUBINFEUDATING SUBINFEUDATION SUBINFEUDATORY SUFFERABLENESS SUFFRAGANSHIPS
SUFFUMIGATIONS SULFADIMIDINES SULFAMETHAZINE SULFANILAMIDES SULFINPYRAZONE
SULFONMETHANES SULFURISATIONS SULFURIZATIONS SUPERFETATIONS SUPERFOETATION
SYNCHROFLASHES TABLESPOONFULS TABLESPOONSFUL TARIFFICATIONS TASTEFULNESSES
TESTIFICATIONS THANKFULNESSES THENCEFORWARDS THUNDERFLASHES THURIFICATIONS
TRANSFERENTIAL TRANSFORMATION TRANSFORMATIVE TRANSFORMISTIC TRANSFUSIONIST
TRANSMOGRIFIED TRANSMOGRIFIES UNAFFECTEDNESS UNCLASSIFIABLE UNCLASSIFIABLY
UNDERSTAFFINGS UNFADINGNESSES UNFAITHFULNESS UNFASHIONABLES UNGRACEFULNESS
UNGRATEFULNESS UNLAWFULNESSES UNPROFESSIONAL UNSATISFACTION UNSATISFACTORY
UNSPECIFICALLY UNTHANKFULNESS UNTHRIFTIHEADS UNTHRIFTYHEADS UNTRANSFERABLE
UNWATCHFULNESS VERBIFICATIONS VERIFIABLENESS VERSIFICATIONS VITRIFICATIONS
VOUCHSAFEMENTS WASTEFULNESSES WATCHFULNESSES WATERFLOODINGS WATERPROOFINGS
WATERPROOFNESS WEARIFULNESSES WRATHFULNESSES YUPPIFICATIONS ZINCIFICATIONS
ZINKIFICATIONS ZOMBIFICATIONS