15 letters
- orientationally21
- orthogonalities21
- oscillographies27
- overachievement32
- overdiversified28
- overdiversities24
- overingenuities24
- overintensities21
- overstabilities23
- paranormalities23
- parasexualities27
- parthenocarpies27
- particularities23
- patentabilities23
- pathogenicities26
- penetrabilities23
- perdurabilities24
- perishabilities24
- pharmacognosies29
- phenomenologies28
- photomultiplier29
- phototoxicities30
- physiotherapies27
- phytotoxicities32
- pneumonectomies30
- preferabilities25
- preinterviewing29
- preponderancies27
- profitabilities25
- progressivities24
- promotabilities25
- proprietorships26
- prosopographies28
- prostatectomies24
- provincialities27
- pseudoscientist24
- psychobiologies31
- psychohistories27
- psychosurgeries28
- psychotherapies30
- punishabilities26
- pusillanimities25
- quadruplicities34
- quincentenaries31
- radioactivities23
- reasonabilities20
- recalcitrancies26
- recallabilities24
- reeligibilities22
- reflectometries25
- reformabilities25
- refractometries24
- refundabilities25
- remediabilities23
- repairabilities22
- repeatabilities22
- replicabilities26
- resectabilities22
- resistibilities19
- retroactivities22
- reversibilities23
- revolutionaries22
- roentgenologies22
- sacrosanctities22
- saprogenicities24
- sedimentologies23
- sigmoidoscopies27
- sinterabilities20
- solderabilities21
- spectrographies28
- spreadabilities23
- squeezabilities38
- stoichiometries23
- superactivities26
- superconvenient29
- superefficiency34
- superfluidities25
- superhumanities26
- supermajorities31
- supernumeraries24
- supersubtleties24
- supersymmetries27
- survivabilities28
- sympathectomies31
- synchronicities27
- telangiectasias22
- thalassocracies24
- theatricalities21
- thyroidectomies26
- tonsillectomies24
- transcendencies25
- triangularities20
- ultraconvenient27
- ultravirilities22
- underactivities25
- unfamiliarities24
- unknowabilities29
- unpunctualities27
- unreliabilities22
- unsociabilities24
- unsuitabilities22
- unworkabilities28
- upgradabilities26
- verifiabilities26
- vulnerabilities26