Or search: plow, embrace, comprehend
2 Syllables: SU
bunches, compass, cumbrous, Dundas, fungus, numbness, oneness, pumice, sumptuous, tonnage, trumpets, unctuous, wondrous, youngest
3 Syllables: USU
Columbus, encompassed

Found 16 words across 2 groupings. Skipped 1 excess word of a similar stem.