1 Syllable: S
2 Syllables: SU
7, Aaron, arid, Baron, barren, beckon, Bedlam, bellum, breasted, Bremen, brethren, Breton, cession, cherub, Clarence, Clemens, Clement, crescent, currant, deaden, deference, Devon, ebbed, Edwin, Ellen, errand, errant, Essen, essence, Evan, felon, fetid, freshman, harem, headed, heaven, Helen, Herod, heron, Hessian, Karen, leaden, leaven, Leben, legend, lemon, Lenin, lessen, lesson, melon, method, nested, parent, peasant, Pelham, penance, pennant, petted, pheasant, pleasant, Plenum, preference, presence, present, pression, Preston, question, reckon, reddened, reference, resin, rested, Reverend, second, session, seven, Sharon, Stephens, tenant, Terence, threaded, threaten, vellum, venom, veteran, weapon, wedded, weren, Wesleyan, Weston
3 Syllables: SUU
3 Syllables: USU
aberrant, accession, aggression, apparent, arrested, assessment, compression, concession, confession, congested, congestion, contestants, contested, depression, digestion, digression, discretion, equestrian, expression, fluorescent, forbearance, impression, incessant, ingestion, inherent, intestine, intrepid, invested, investment, Lieutenant, Magellan, obsession, oppression, pedestrian, possession, predestined, presented, procession, profession, progression, quiescence, quiescent, quintessence, recession, refreshment, regression, relented, repellent, repression, requested, resented, secession, succession, suggested, suggestion, suppression, transgression, transparent, unpleasant, unquestioned
4 Syllables: UUSU
acquiescence, adolescence, adolescent, cerebellum, convalescence, convalescent, effervescence, evanescent, incandescent, indigestion, indiscretion, intercession, iridescent, Mahometan, obsolescence, omnipresence, omnipresent, phosphorescent, prepossessions, represented, retrogression
Found 176 words across 5 groupings. Skipped 58 excess words of a similar stem.