Or search: rot, bunk, guff, filth, bunkum, hogwash, buncombe, obscenity, vulgarism
2 Syllables: SU
audit, clotted, cockpit, dotted, jotted, knotted, lauded, nodded, opted, optic, plaudits, plotted, potted, prodded, Roderick, rotted, spotted, squatted, topic, toxic, tropic, trotted
3 Syllables: USU
allotted, applauded, aquatic, chaotic, defrauded, despotic, erotic, exotic, hypnotic, narcotic, neurotic, quixotic, spasmodic, unspotted
4 Syllables: UUSU
episodic, idiotic, microscopic, patriotic, periodic, philanthropic, superadded
5 Syllables: UUUSU
antibiotics

Found 44 words across 4 groupings. Skipped 4 excess words of a similar stem.