2 Syllables: SU
blemish, checklist, chemist, cherish, clerics, credits, denis, dennis, devilish, dwelleth, else's, epics, essex, ethics, fairest, fetish, flemish, garish, greenwich, harris, hellish, menace, merits, paris, parish, perish, prelates, premise, reddish, relics, relish, selfish, sheriff, sheriff's, tennis, venice
3 Syllables: USU
aesthetics, athletics, cosmetics, domestics, embellish, genetics, hysterics, kinetics, obstetrics, poetics, polemics, replenish, unblemished, unselfish
4 Syllables: UUSU
academics, epidemics, sacrilegious

Found 53 words across 3 groupings. Skipped 7 excess words of a similar stem.