3 Syllables: SUU
frantically, nationally, naturally, rationally
4 Syllables: SUUU
adequacy, casually, definitely, Fortunately, infinitely, laterally, obstinately, passionately
4 Syllables: USUU
unnaturally
5 Syllables: USUUU
affectionately, diagonally, inadequately, indefinitely, inordinately, proportionately, unanimously, unfortunately
6 Syllables: UUSUUU
disproportionately, indiscriminately

Found 23 words across 5 groupings.