Or search: neatness, spruceness
2 Syllables: SU
bilious, busiest, hideous, idiots, igneous, piteous, prettiest, serious, vitreous
3 Syllables: SUU
dizziness, giddiness, pitiless, weariness
3 Syllables: USU
amphibious, delirious, fastidious, imperious, initiates, insidious, invidious, lascivious, Mauritius, mysterious, oblivious, perfidious, punctilious
4 Syllables: UUSU
deleterious, Dionysius, ignominious, supercilious

Found 30 words across 4 groupings.