2 Syllables: SU
breakfast, deadliest, dexterous, extras, headless, lettuce, necklace, nexus, plexus, readiest, reckless, redness, sections, sexes, Texas, wreckage
3 Syllables: USU
affections, collections, complexions, conceptions, connections, connexions, corrections, correctness, deceptions, directions, directness, elections, exceptions, infections, infectious, inflections, injections, inspections, objections, perceptions, perfections, projections, prospectus, protections, receptions, reflections, selections
4 Syllables: UUSU
imperfections, insurrections, intersections, misconceptions, preconceptions, predilections, recollections
Found 50 words across 3 groupings. Skipped 1 excess word of a similar stem.