15 letters
- platitudinarian23
- plenipotentiary26
- polysaccharides30
- popularizations33
- postmillenarian25
- prearrangements25
- predestinarians21
- prekindergarten27
- premillenarians25
- proletarianised21
- proletarianises20
- proletarianized30
- proletarianizes29
- quarrelsomeness30
- quarterfinalist30
- quatercentenary32
- quincentenaries31
- reactionaryisms24
- regardfulnesses24
- regularizations29
- repolarizations29
- revolutionaries22
- revolutionarily25
- rudimentariness22
- secondarinesses21
- secularizations30
- semidocumentary29
- semilogarithmic29
- semitransparent23
- separablenesses23
- septuagenarians23
- sesquicarbonate32
- sesquicentenary32
- softheartedness22
- solitudinarians20
- spinthariscopes27
- standardization28
- straightforward26
- subproletariats23
- substitutionary23
- supernumeraries24
- superparasitism25
- tachyarrhythmia31
- tarsometatarsus19
- temerariousness20
- temporarinesses22
- tenderheartedly23
- teratocarcinoma25
- totalitarianism20
- totalitarianize26
- transparentized30
- transparentizes29
- transparentness21
- triangularities20
- trueheartedness20
- ultramarathoner23
- uncomplimentary33
- unearthlinesses21
- unextraordinary28
- unfamiliarities24
- unguardednesses23
- uniformitarians24
- unparliamentary27
- unrevolutionary26
- utilitarianisms21
- valetudinarians24
- vascularization34
- vicariousnesses24
- visionarinesses21
- voluntarinesses23
- warmheartedness25
- warrantableness24
- wearisomenesses22
- weatherboarding27