Or search: bate, curb, damp, mild, tame, adult, mince, modest, modify, soften, subdue, temper, weaken, conquer, grownup
3 Syllables: SUU
commonest, cooperate, doctorate, dominate, moderates, nominate, novelist, obdurate, oftenest, operate, oscillate, propagate, proselytes, tolerate, waterway
4 Syllables: USUU
accommodate, conglomerate, corroborate, denominate, exonerate, geologist, inaugurate, predominate, psychologist

Found 24 words across 2 groupings. Skipped 9 excess words of a similar stem.