3 Syllables: SUU
decency, decently, evenly, frequencies, frequency, frequently, leniency, recently, regency
3 Syllables: UUS
vehemently
4 Syllables: USUU
conveniently, expediency, indecency, infrequently, ingeniously, obediently, unevenly, unfrequently

Found 18 words across 3 groupings.