Or search: treason, knavery, betrayal, treachery, dishonesty, insidiousness, perfidiousness
3 Syllables: SUU
furtively, vertically, worthily
4 Syllables: USUU
adversity, diversities, diversity, fraternity, imperfectly, infirmities, infirmity, maternity, paternity, unmercifully, unworthily

Found 14 words across 2 groupings.