Or search: loudly, obstreperously
3 Syllables: SUU
frantically, nationally, naturally, rationally
4 Syllables: SUUU
adequacy, barbarously, casually, dangerously, dexterously, generously, humorously, laterally, passionately, rigorously, treacherously, vigorously
4 Syllables: USUU
unnaturally
5 Syllables: USUUU
diagonally, dispassionately, inadequately, unanimously

Found 21 words across 4 groupings.