13 letters
- semidiameters20
- shamelessness20
- sledgehammers25
- slipstreaming23
- somnambulated26
- somnambulates25
- somnambulisms28
- somnambulists25
- squeamishness29
- steamrollered19
- sulfanilamide24
- superfamilies24
- temperamental24
- tetradynamous21
- thermodynamic28
- trampolinings24
- trampolinists21
- transaminases18
- triamcinolone22
- tsutsugamushi23
- ultrafamiliar22
- ultramarathon21
- ultramilitant20
- ultramontanes20
- unambiguously28
- unfamiliarity24
- ungrammatical27
- yellowhammers28