3 Syllables: SUU
physically, rigidly
4 Syllables: USUU
activities, activity, artistically, complicity, declivity, duplicity, ethnicity, exquisitely, passivity, plasticity, publicity, simplicity, specifically, statistically
5 Syllables: UUSUU
authenticity, catholicity, eccentricities, inactivity, multiplicity, objectivity, periodicity, productivity, realistically, receptivity, scientifically, sensitivity, subjectivity
6 Syllables: UUUSUU
characteristically

Found 30 words across 4 groupings.