Or search: link, climax, straits, junction, landmark, connexion, happening, occurrent, crossroads, occurrence, criticality, articulation
2 Syllables: SU
blunder, bumper, Bunker, comer, comfort, drummer, drunkard, Dunkirk, gunner, humbler, hundred, hunger, hunter, lumber, mongers, Munster, number, plumber, plunder, puncture, runner, slumber, Somers, summer, Sumner, sunburnt, sundered, thunder, tumbler, under, wonder, younger, youngster
3 Syllables: USU
asunder, columnar, conjuncture, discomfort, encumber, midsummer, outnumber, unnumbered
4 Syllables: UUSU
unencumbered

Found 42 words across 3 groupings. Skipped 28 excess words of a similar stem.