There are 407 fifteen-letter words containing A, E, H, L and T, https://www.bestwordlist.com/c/a/5/15letterwordswithaehlt.htm
ACANTHOCEPHALAN ACCOMPLISHMENTS AEROLITHOLOGIES ALCOHOLOMETRIES
ALPHABETISATION ALPHABETIZATION ALUMINOTHERMIES AMPHITHEATRICAL
ANAESTHESIOLOGY ANAESTHETICALLY ANTHROPOLATRIES ANTICHOLESTEROL
ANTICHOLINERGIC ANTIDIARRHOEALS ANTIFASHIONABLE ANTIHELMINTHICS
ANTITHEORETICAL APHELIOTROPISMS ARCHEOZOOLOGIST ARCHGENETHLIACS
ARCHITECTURALLY ATHEROSCLEROSES ATHEROSCLEROSIS ATHEROSCLEROTIC
ATMOSPHERICALLY AUTHORITATIVELY BALNEOTHERAPIES BATHOMETRICALLY
BATHYMETRICALLY BIBLIOTHECARIES BIBLIOTHERAPIES BIOMATHEMATICAL
BLAMEWORTHINESS BLETHERANSKATES BRACHYDACTYLIES BREATHABILITIES
BREMSSTRAHLUNGS BROKENHEARTEDLY CATECHISTICALLY CEPHALOCHORDATE
CEPHALOTHORACES CEPHALOTHORACIC CEPHALOTHORAXES CHANGEABILITIES
CHANNELISATIONS CHANNELIZATIONS CHANNELOPATHIES CHARACTERISABLE
CHARACTERIZABLE CHARGEABILITIES CHEMOTACTICALLY CHEMOTROPICALLY
CHLOROTHIAZIDES CHLORTHALIDONES CHOLESTEROLEMIA CHOLESTYRAMINES
CHOLINESTERASES CHRESTOMATHICAL CLIMATOGRAPHIES COLDHEARTEDNESS
COLLENCHYMATOUS CROTONALDEHYDES CYANOETHYLATING CYANOETHYLATION
CYTOPATHOLOGIES DACTYLOGRAPHERS DACTYLOGRAPHIES DEATHLESSNESSES
DECHLORINATIONS DECIPHERABILITY DEPHLOGISTICATE DEPHOSPHORYLATE
DERMATOGLYPHICS DESULPHURATIONS DETACHABILITIES DIAHELIOTROPISM
DICHLOROETHANES DICHLOROMETHANE DIMETHYLANILINE DISENCHANTINGLY
DISENTHRALLMENT DISENTHRALMENTS DISESTABLISHING DISHEARTENINGLY
DISTINGUISHABLE EDRIOPHTHALMIAN EDRIOPHTHALMOUS ELECTROCHEMICAL
ELECTROGRAPHIES ELECTROMYOGRAPH ELEUTHERODACTYL ELEUTHEROMANIAS
ELEUTHEROPHOBIA ENCEPHALITOGENS ENCEPHALOPATHIC ENCEPHALOTOMIES
ENDOTHERMICALLY EPITHELIALISING EPITHELIALIZING EPITHELIOMATOUS
EPITHELISATIONS EPITHELIZATIONS ERYTHROMELALGIA ETHEREALISATION
ETHEREALIZATION ETHNOBIOLOGICAL ETHNOHISTORICAL EUPHEMISTICALLY
EXCHANGEABILITY EXHAUSTLESSNESS FAITHLESSNESSES FETISHISTICALLY
FLUOROPHOSPHATE GENETHLIALOGIES GEOSTROPHICALLY GLUTARALDEHYDES
GRANDFATHERLIER GRANDMOTHERLIER HABITABLENESSES HAEMAGGLUTINATE
HAEMAGGLUTININS HAEMOFLAGELLATE HALFHEARTEDNESS HALFPENNYWORTHS
HEADMASTERLIEST HEALTHFULNESSES HEARTBREAKINGLY HEARTLESSNESSES
HELIOMETRICALLY HELIOTROPICALLY HEMAGGLUTINATED HEMAGGLUTINATES
HEMICRYSTALLINE HEMOFLAGELLATES HEPATICOLOGICAL HEPATICOLOGISTS
HERMENEUTICALLY HETEROCERCALITY HETERODACTYLOUS HETEROGRAPHICAL
HETEROSEXUALITY HETEROSOCIALITY HETEROTHALLISMS HEXACHLORETHANE
HISTOCHEMICALLY HISTOCOMPATIBLE HOLOCRYSTALLINE HOLOMETABOLISMS
HOMEOPATHICALLY HOMOCENTRICALLY HOMOSEXUALITIES HOMOSOCIALITIES
HONOURABILITIES HORIZONTALITIES HYDROMETALLURGY HYDROMETRICALLY
HYDROXYLAPATITE HYGROMETRICALLY HYPERCATABOLISM HYPERCATALECTIC
HYPERCRITICALLY HYPERFUNCTIONAL HYPERINFLATIONS HYPERMETABOLISM
HYPERMETROPICAL HYPERMUTABILITY HYPERSALINITIES HYPERSALIVATION
HYPERSTIMULATED HYPERSTIMULATES HYPERVENTILATED HYPERVENTILATES
HYPOCRYSTALLINE HYPOVENTILATION HYPSOMETRICALLY IMPERISHABILITY
INHERITABLENESS INHOSPITALITIES INTERBEHAVIORAL INTERCHANGEABLE
INTERCHANGEABLY INTERPHALANGEAL INTERSCHOLASTIC KAFFEEKLATSCHES
KINESTHETICALLY LABYRINTHITISES LEGISLATORSHIPS LEUCOCYTHAEMIAS
LEXICOGRAPHISTS LICENTIATESHIPS LIEUTENANTSHIPS LIGHTFASTNESSES
LIONHEARTEDNESS LOATHSOMENESSES LOPHOBRANCHIATE LYMPHADENITISES
LYMPHADENOPATHY LYMPHOADENOMATA LYMPHOCYTOPENIA MACHINABILITIES
MAGNETOCHEMICAL MARSHMALLOWIEST MATCHLESSNESSES MECHANISTICALLY
MERCHANTABILITY MESATICEPHALIES MESATICEPHALOUS METABISULPHITES
METALLOGRAPHERS METALLOGRAPHIES METALLOGRAPHIST METAMORPHICALLY
METATHEORETICAL METHAEMOGLOBINS METHOXYFLURANES METHYLPHENIDATE
METHYLXANTHINES MOUTHWATERINGLY MULTICHARACTERS MULTITHREADINGS
MULTIWAVELENGTH NEMATHELMINTHIC NEPHROBLASTOMAS NEUROPATHICALLY
NEUROPATHOLOGIC NONHETEROSEXUAL NONHOSPITALISED NONHOSPITALIZED
NONHYSTERICALLY NONMATHEMATICAL NONMETAPHORICAL NONTHEISTICALLY
NORTHEASTERLIES NORTHEASTWARDLY NORTHWESTWARDLY OLIGOCYTHAEMIAS
OPHTHALMOLOGIES OPHTHALMOMETERS OPHTHALMOPLEGIA OPHTHALMOSCOPES
ORCHESTRATIONAL ORNITHODELPHIAN ORTHOGONALITIES ORTHOPAEDICALLY
OSTEOPATHICALLY PALAEOANTHROPIC PALAEOETHNOLOGY PALAEOGRAPHISTS
PALAEONTOGRAPHY PALAEOPATHOLOGY PALAEOPHYTOLOGY PAMPHLETEERINGS
PANTHEISTICALLY PARAHELIOTROPIC PARENTHETICALLY PERIPHERALITIES
PERISHABILITIES PETROCHEMICALLY PHALLOCENTRISMS PHANTASMALITIES
PHARMACEUTICALS PHENETHYLAMINES PHENOLPHTHALEIN PHENOMENALISTIC
PHENOMENALITIES PHENYLBUTAZONES PHENYLKETONURIA PHENYLTHIOUREAS
PHILOSOPHASTERS PHOSPHORYLATIVE PHOTOCHEMICALLY PHOTODEGRADABLE
PHOTODUPLICATED PHOTODUPLICATES PHOTOELASTICITY PHOTOELECTRICAL
PHOTOGEOLOGICAL PHOTOMECHANICAL PHOTOMETRICALLY PHOTOTELEGRAPHS
PHOTOTELEGRAPHY PHTHALOCYANINES PHYLLOSILICATES PHYTOCHEMICALLY
PHYTOFLAGELLATE PLAINCLOTHESMAN PLAINCLOTHESMEN PLATYHELMINTHIC
PLETHYSMOGRAPHS PLETHYSMOGRAPHY POLYARTHRITIDES POLYARTHRITISES
POLYCHLORINATED POLYSYNTHETICAL PREESTABLISHING PREHISTORICALLY
PSYCHOGENETICAL PSYCHOSEXUALITY PSYCHROMETRICAL PTERYLOGRAPHIES
PULMOBRANCHIATE PUNISHABILITIES PYROTECHNICALLY RADICULOPATHIES
RADIOTELEGRAPHS RADIOTELEGRAPHY RADIOTELEPHONED RADIOTELEPHONES
RADIOTELEPHONIC REESTABLISHMENT REHABILITATIONS REHOSPITALISING
REHOSPITALIZING RHEUMATOLOGICAL RHEUMATOLOGISTS RHINOSCLEROMATA
RIGHTABLENESSES SCATHEFULNESSES SCHILLERISATION SCHILLERIZATION
SCHOOLMASTERING SCHOOLMASTERISH SCHOOLTEACHINGS SCLEROTHERAPIES
SCRATCHBUILDERS SEARCHABILITIES SELENOGRAPHISTS SEMILOGARITHMIC
SKETCHABILITIES SLAUGHTERHOUSES SOPHISTICATEDLY SOUTHEASTERLIES
SOUTHWESTWARDLY SPELEOTHERAPIES SPHAEROCRYSTALS STADHOLDERSHIPS
STADTHOLDERATES STADTHOLDERSHIP STEEPLECHASINGS STEGOCEPHALIANS
STEREOGRAPHICAL STOECHIOLOGICAL STRATOSPHERICAL STREPHOSYMBOLIA
SULFAMETHAZINES SULPHACETAMIDES SULPHATHIAZOLES SULPHONMETHANES
SYMPATHETICALLY TACHOMETRICALLY TACHYMETRICALLY TEACHABLENESSES
TECHNICALNESSES TECHNOLOGICALLY TELAUTOGRAPHIES TELEGRAPHICALLY
TELEPHOTOGRAPHS TELEPHOTOGRAPHY TENDERHEARTEDLY TETARTOHEDRALLY
TETRAETHYLLEADS TETRAMETHYLLEAD THALAMENCEPHALA THALASSOCRACIES
THALASSOGRAPHER THALASSOTHERAPY THALATTOCRACIES THANKLESSNESSES
THAUMATOLATRIES THEATRICALISING THEATRICALITIES THEATRICALIZING
THEOLOGISATIONS THEOLOGIZATIONS THEOREMATICALLY THEOSOPHISTICAL
THERAPEUTICALLY THERMALISATIONS THERMALIZATIONS THERMODYNAMICAL
THERMOREGULATED THERMOREGULATES THERMOREGULATOR THERMOSTABILITY
THINKABLENESSES THORACOPLASTIES THREMMATOLOGIES TOUCHABLENESSES
TRIBROMOETHANOL TRICHLOROACETIC TRICHLOROETHANE TRIHALOMETHANES
TRIMETHYLAMINES TRIPHENYLAMINES ULTRAMARATHONER UNAUTHENTICALLY
UNCHANGEABILITY UNCHRISTIANLIKE UNCOPYRIGHTABLE UNEARTHLINESSES
UNHEALTHFULNESS UNHEALTHINESSES UNTEACHABLENESS UNTHINKABLENESS
UNTHREATENINGLY WEATHERLINESSES WELTANSCHAUUNGS