18 letters
- preposterousnesses26
- presumptuousnesses31
- pronounceabilities31
- propertylessnesses28
- pseudonymousnesses31
- pseudotuberculoses32
- psychophysiologies38
- puzzleheadednesses46
- quantitativenesses34
- quasiperiodicities35
- questionablenesses34
- radiosensitivities24
- rambunctiousnesses31
- rechromatographies33
- remunerativenesses28
- reprehensibilities28
- representationally27
- representativeness27
- representativities26
- sacrilegiousnesses26
- satisfactorinesses25
- semidomestications29
- semipermeabilities31
- semiprofessionally32
- shortsightednesses26
- simplemindednesses32
- simultaneousnesses26
- soporiferousnesses26
- spectrohelioscopes33
- sphygmomanometries37
- stereoregularities22
- stoutheartednesses23
- subconsciousnesses31
- substitutabilities27
- superciliousnesses28
- superconglomerates32
- superintelligences31
- supernaturalnesses26
- supersensitivities27
- supranationalities25
- thermoluminescence36
- thermoplasticities30
- thrombophlebitides36
- transmissibilities26
- transportabilities26
- triboelectricities28
- triboluminescences34
- trichloroethylenes30
- ultraconservatives32
- unaccountabilities32
- unassailablenesses26
- unattractivenesses28
- unchangeablenesses33
- uncharitablenesses30
- uncompromisingness36
- unconscionableness33
- unconvincingnesses36
- ungrammaticalities32
- unintelligibleness30
- unpredictabilities31
- unprinciplednesses33
- unprofitablenesses31
- unreasonablenesses26
- unresponsivenesses29
- unrestrainednesses23
- unsatisfactoriness27
- unscrupulousnesses31
- unseasonablenesses26
- unsubstantialities26
- vaingloriousnesses28
- weatherproofnesses30