15 letters
- strenuousnesses19
- streptobacillus27
- subreptitiously26
- subterraneously24
- sulfurousnesses23
- sumptuousnesses25
- superfluousness26
- superstitiously23
- surreptitiously23
- susceptibleness27
- suspensefulness26
- synchronousness26
- tarsometatarsus19
- temerariousness20
- tempestuousness24
- tenaciousnesses21
- tendentiousness20
- treacherousness22
- tremulousnesses22
- troublousnesses22
- trustworthiness22
- tyrannosauruses21
- ultrafastidious22
- unceremoniously28
- unconsciousness26
- unfossiliferous25
- unmelodiousness24
- unobtrusiveness26
- unpretentiously25
- unrighteousness23
- unseriousnesses19
- venturousnesses23
- veraciousnesses24
- vexatiousnesses28
- vicariousnesses24
- vicissitudinous26
- vivaciousnesses28
- voraciousnesses24