Or search: plenteously
2 Syllables: SU
boundary
3 Syllables: SUU
courteously, curiously, furiously, gloriously, hideously, obviously, previously, seriously, studiously, variously
4 Syllables: USUU
erroneously, harmoniously, imperiously, industriously, injuriously, insidiously, laboriously, luxuriously, mysteriously, notoriously, precariously, spontaneously, victoriously
5 Syllables: UUSUU
ignominiously, instantaneously, simultaneously, unaccountably
6 Syllables: UUUSUU
contemporaneously, unceremoniously

Found 30 words across 5 groupings.