2 Syllables: SU
Aldrich, broadest, College, Doris, faultless, Hollis, knowledge, Maurice, olive, ostrich, plaudits, polish, profits, Psalmist, Romish, Scottish, solstice, sonnets, sophist, tallest, topics, tropics, Wallace, Wallis
3 Syllables: USU
abolish, acknowledge, admonish, astonish, demolish, deposits, impoverish, narcotics, unpolished
4 Syllables: UUSU
economics, electronics, unacknowledged
5 Syllables: UUUSU
antibiotics

Found 37 words across 4 groupings. Skipped 8 excess words of a similar stem.