2 Syllables: SU
7, aaron, airing, baring, baron, barren, bearing, beckon, bedding, bedlam, begging, bellum, bending, benson, bentham, benton, betting, blending, blessing, bremen, brethren, breton, caring, cession, charing, checking, clarence, cleansing, clemens, clement, crescent, currant, daring, deaden, deference, denning, destined, devon, dreading, dredging, drenching, dressing, dwelling, ebbing, edging, edwin, ellen, emblem, ending, engine, ensign, entrance, errand, errant, erring, essen, essence, etching, evan, felling, felon, fencing, fenton, fetching, flaring, fleming, freshened, fretting, getting, glaring, guessing, harem, heading, heaven, helen, helen's, heron, herring, hessian, jenkins, jennings, jensen, jesting, karen, kenyon, larynx, leaden, leaven, leben, legend, lemon, lending, lengthen, lessen, lessing, lesson, letting, leveling, levin, meddling, melon, mending, mention, nesting, nestling, netting, pairing, parent, paring, peasant, pecking, pelham, penance, penchant, pendant, pendent, pending, penguin, pennant, pension, pharynx, pheasant, pleasant, pledging, plenum, preference, presence, present, pressing, pression, preston, quenching, quentin, question, reading, reckon, reddened, reference, remnant, rending, renting, resin, resting, reverend, second, selling, semblance, sending, sensing, sentence, sentient, session, setting, settling, seven, sharing, sharon, shedding, shelling, sketching, smelling, sparing, spelling, spending, spreading, squaring, staring, stemming, stephens, stepping, strengthen, stressing, stretching, swearing, sweating, swelling, tearing, telling, temperance, tempting, tenant, tending, tendon, tension, terence, testing, threading, threaten, threshing, treading, trembling, trenchant, trenton, vellum, vengeance, venom, venting, vesting, veteran, weapon, wearing, wedding, welling, weren, weston, wetting, wrecking, wrenching, wresting, wrestling, yelling
3 Syllables: SUU
3 Syllables: USU
aberrant, abetting, abstention, accession, addressing, aggression, alleging, amending, amendment, apparent, arresting, ascendant, ascending, ascension, assembling, assenting, assessing, assessment, attempting, attendance, attendant, attending, attention, attesting, avenging, begetting, besetting, caressing, cementing, clandestine, commencement, commencing, commending, comparing, compelling, compendium, compressing, compression, concession, condemning, condensing, confessing, confession, consenting, contending, contenting, contention, contentment, contestants, contesting, convention, declaring, declension, defendant, defending, dependant, dependence, dependent, depending, depressing, depression, descendant, descending, despairing, detention, digression, dimension, discretion, dispelling, dispensing, dissension, dissenting, distressing, endeavoring, entrenchments, excelling, exempting, exemption, expelling, expending, expressing, expression, extending, extension, fermenting, fluorescent, forbearance, forbearing, foretelling, forgetting, impairing, impelling, impending, impressing, impression, incessant, indwelling, inherent, intending, intention, intestine, inventing, invention, investing, investment, lamenting, lieutenant, magellan, millennium, momentum, obsession, offending, oppressing, oppression, possessing, possession, predestined, preparing, presenting, presentment, pretending, pretension, preventing, prevention, procession, professing, profession, progressing, progression, propelling, quiescence, quiescent, quintessence, rebelling, recession, redemption, refreshing, regression, regretting, remembering, remembrance, repairing, repellent, repelling, repentance, repentant, repenting, repressing, repression, requesting, resemblance, resembling, resenting, resentment, resplendent, retention, retrenchment, secession, succession, suggesting, suppressing, suppression, suspending, suspension, transcendence, transcendent, transcending, transgressing, transgression, transparent, unbending, undressing, unending, unerring, unpleasant, unsettling, unsparing, upsetting
4 Syllables: UUSU
5 Syllables: UUUSU

Found 439 words across 5 groupings. Skipped 101 excess words of a similar stem.