Or search: burial, ceremony, interment, ceremonial, entombment, observance, inhumation
3 Syllables: SUU
beautiful, crucible, funerals, Juvenal, juvenile, movable, moveable, mutable, numeral, suitable, tubercle, usable, usual
4 Syllables: USUU
deducible, excusable, immovable, immoveable, immutable, inscrutable, reducible, removable, renewable, unsuitable
5 Syllables: UUSUU
constitutional, indisputable, inexcusable, institutional, irreducible, irrefutable, longitudinal
6 Syllables: UUUSUU
unconstitutional

Found 31 words across 4 groupings. Skipped 1 excess word of a similar stem.