2 Syllables: SU
ashes, average, baggage, batches, cabbage, carriage, castings, catches, clashes, classes, crashes, damage, dashes, Fascist, fastenings, flashes, gases, glasses, grasses, hatches, lashes, lavish, manage, masses, massive, matches, matchless, package, passage, passes, passeth, passive, patches, pathless, rapids, ravage, ravished, saplings, sashes, savage, scratches, snatches, splashes, trappings
3 Syllables: USU
Agassiz, attaches, combative, despatches, dispatches, impassive, pugnacious, rapacious, surpasses, unchallenged
4 Syllables: UUSU
Found 55 words across 3 groupings. Skipped 8 excess words of a similar stem.