13 letters
- mythologizing35
- mythopoetical27
- naphthylamine28
- naturopathies20
- nephropathies24
- neurasthenias18
- neurasthenics21
- nitromethanes20
- nonpathogenic26
- nontheatrical21
- norethindrone19
- normothermias22
- northeasterly19
- northeastward20
- northwesterly22
- northwestward23
- nothingnesses20
- openmouthedly27
- ophthalmology29
- opisthobranch27
- ornithischian22
- ornithologies19
- ornithologist19
- orthodontists17
- orthoepically25
- orthogonality21
- orthogonalize28
- orthographies22
- orthopterists18
- orthopteroids19
- overbreathing25
- overlengthens24
- overwithholds26
- pantheistical23
- pantothenates20
- paraesthesias18
- parasyntheses21
- parasynthesis21
- parasynthetic24
- parathormones22
- parenthesized29
- parenthesizes28
- parenthetical23
- parthenocarpy27
- pathogenicity26
- pathognomonic28
- phenanthrenes23
- phenothiazine31
- philanthropic28
- photocathodes24
- photosynthate23
- phycoerythrin28
- physiotherapy27
- phytopathogen28
- platyhelminth28
- plethysmogram29
- poikilotherms26
- polycythemias29
- polyethylenes25
- polyurethanes23
- postholocaust23
- preanesthetic22
- procathedrals23
- psychasthenia26
- psychasthenic29
- psychopathics31
- psychopathies28
- psychotherapy30
- pyrimethamine27
- quadrillionth29
- quintillionth29
- radiothoriums20
- reauthorizing28
- remythologize32
- restrengthens19
- resynthesized28
- resynthesizes27
- retinopathies19
- rhadamanthine23
- rhythmicities25
- rhythmization32
- rutherfordium24
- ruthfulnesses22
- seaworthiness19
- semimonthlies23
- semisynthetic24
- softheartedly22
- southeasterly19
- southeastward20
- southernwoods21
- southwesterly22
- southwestward23
- stichomythias25
- stichomythies25
- strengtheners19
- strengthening22
- strophanthins22
- superathletes20
- superstrength22
- superthriller21
- swarthinesses19
- sympathectomy31
- sympatholytic29
- synaesthesias18
- synarthrodial20
- synthetically25
- terephthalate21
- thalassaemias19
- thalassocracy24
- thalassocrats19
- thanatologies19
- thanatologist19
- thanklessness22
- thanksgivings29
- thaumaturgies22
- thaumaturgist22
- theatergoings20
- theatricalism22
- theatricality21
- theatricalize28
- thenceforward26
- theocentrisms22
- theologically25
- theophyllines25
- theoretically22
- theoreticians19
- theorizations25
- theriomorphic26
- thermochemist26
- thermocouples26
- thermodynamic28
- thermoelement23
- thermoforming27
- thermographic28
- thermometries21
- thermonuclear24
- thermophilous25
- thermoplastic25
- thermosetting21
- thermospheres23
- thermospheric26
- thermostating21
- thermostatted19
- thermotropism24
- thiabendazole30
- thigmotropism26
- thimblerigged27
- thimblerigger26
- thinkableness25
- thioridazines26
- thirstinesses16
- thoracotomies21
- thoroughbrace26
- thoroughbreds24
- thoroughfares23
- thoroughgoing25
- thoroughworts23
- thoughtlessly24
- thrasonically23
- threadinesses17
- threateningly22
- thriftinesses19
- throatinesses16
- throatlatches21
- thrombokinase26
- throttleholds20
- thunderclouds24
- thundershower23
- thunderstones19
- thunderstorms21
- thunderstrike22
- thunderstroke22
- thunderstruck26
- thymectomized36
- thymectomizes35
- thyroglobulin26
- thyroidectomy26
- thyroiditises18
- thyrotrophins23
- toothbrushing24
- toothsomeness19
- transthoracic22
- trichothecene24
- trimethoprims24
- tritheistical19
- trothplighted24
- trustworthily22
- ultramarathon21
- ultraorthodox25
- uncouthnesses22
- underclothing25
- understrength21
- unearthliness19
- unforthcoming29
- unhealthiness21
- unorthodoxies25
- unsympathetic28
- untheoretical21
- unthreatening21
- untrustworthy23