19 letters
- paleoclimatologists33
- paleogeographically39
- paradichlorobenzene43
- parasympathomimetic41
- parathyroidectomies33
- parthenogenetically35
- perspicaciousnesses33
- pharmacodynamically44
- phenomenalistically37
- phenylpropanolamine40
- phenylthiocarbamide40
- phonocardiographies36
- phosphatidylcholine40
- phosphoenolpyruvate41
- phosphofructokinase41
- phosphoglucomutases40
- phosphomonoesterase33
- photoconductivities37
- photodecompositions35
- photodisintegrating31
- photodisintegration29
- photofluorographies36
- photointerpretation29
- photoreconnaissance33
- photosensitizations35
- phytogeographically42
- phytohemagglutinins39
- polychromatophilias39
- polyesterifications32
- polyribonucleotides35
- postmillenarianisms32
- posttranscriptional31
- professionalization37
- proletarianizations34
- pseudosophisticated33
- psychopharmacologic46
- psychophysiological43
- psychophysiologists39
- psychotomimetically42
- radioallergosorbent28
- radiopharmaceutical36
- reconceptualization41
- reindustrialization33
- reinstitutionalized33
- reinstitutionalizes32
- representationalism28
- representationalist25
- reticuloendothelial30
- revolutionarinesses27
- sanctimoniousnesses29
- semiconsciousnesses31
- sentimentalizations35
- spectrofluorimeters33
- spectrofluorometers33
- spectrofluorometric36
- spectrophotometries33
- splendiferousnesses30
- stereophotographies31
- stereospecificities31
- straightforwardness31
- superadministrators28
- superconductivities36
- superspecialization40
- symptomatologically40
- territorializations30
- thermoelectricities31
- thermoluminescences37
- thermoperiodicities31
- transformationalist28
- transmogrifications32
- transubstantiations26
- tridimensionalities26
- ultracentrifugation32
- ultracontemporaries31
- ultrasegregationist26
- unapproachabilities36
- unceremoniousnesses30
- uncompetitivenesses35
- unconscionabilities33
- unconstitutionality30
- uncontrollabilities31
- unconventionalities32
- undemonstrativeness31
- underrepresentation27
- unexceptionableness40
- unfashionablenesses32
- unidimensionalities28
- unpretentiousnesses27