Or search: lull, poise, aplomb, repose, serenity, composure, stillness, placidity, equanimity, temperament, tranquility, tranquillity, windlessness, imperturbability, imperturbableness
2 Syllables: SU
baldness, bronzes, commas, conduits, Congress, conscious, constructs, dramas, flawless, fondest, fondness, genres, haunches, homage, honest, jaundice, knowledge, launches, lawless, longest, Monmouth, monstrous, olive, Paulus, pompous, pontiff, promise, promptness, smallest, smallness, solace, strongest, Thomas, Wallace, walnuts
3 Syllables: SUU
pianist
3 Syllables: USU
accomplice, Adolphus, Adonis, Cornwallis, dishonest, responses, subconscious, unconscious

Found 44 words across 3 groupings. Skipped 1 excess word of a similar stem.