15 letters
- photodegradable28
- pigheadednesses25
- pinheadednesses24
- platinocyanides27
- poliomyelitides26
- polyacrylamides31
- polynucleotides28
- polysaccharides30
- ponderousnesses22
- postdevaluation26
- predestinarians21
- predestinations21
- predevaluations26
- predevelopments31
- prekindergarten27
- preponderancies27
- preponderations24
- prepresidential24
- pseudepigraphon31
- psychedelically34
- reconsideration21
- redetermination21
- ribonucleosides25
- ribonucleotides25
- roundheadedness23
- septendecillion26
- sidesplittingly26
- solderabilities21
- stadtholderates20
- stadtholdership25
- subdevelopments32
- supercalendered26
- superintendence26
- superintendency28
- superintendents23
- swellheadedness25
- tatterdemalions21
- tendentiousness20
- tenderheartedly23
- thunderstricken28
- thunderstriking27
- thyroidectomies26
- transcendencies25
- trichomonacides28
- ultrademocratic27
- ultramodernists22
- unboundednesses25
- undemonstrative26
- underactivities25
- underemphasized36
- underemphasizes35
- underemployment31
- underestimating24
- underestimation22
- underhandedness24
- underinflations24
- underinvestment27
- undernutritions21
- underprivileged29
- underproduction27
- underpublicized39
- understandingly26
- understatements22
- undervaluations25
- undesirableness23
- unguardednesses23
- unprecedentedly29
- verisimilitudes25
- videoconference31
- wonderfulnesses26
- wrongheadedness26