2 Syllables: SU
biggest, bigness, bilious, busiest, citrus, fitness, fittest, hideous, idiots, igneous, mixes, Nicholas, nitrous, piteous, prettiest, quibus, quickness, serious, sickness, strictest, strictness, thickness, vitreous, witness
3 Syllables: SUU
3 Syllables: USU
amphibious, assiduous, delirious, enigmas, eyewitness, fastidious, imperious, initiates, insidious, invidious, lascivious, Mauritius, mysterious, oblivious, perfidious, punctilious, unfitness
4 Syllables: UUSU
Found 49 words across 4 groupings. Skipped 1 excess word of a similar stem.