2 Syllables: SU
bigness, bigot, billet, biscuit, Bishop, Bridget, Christmas, citrus, dearest, digit, fitness, fittest, frigate, grimace, hideous, hillock, igneous, isthmus, limit, listless, millet, minute, minutest, mistress, mixes, nearest, Nicholas, nitrous, Philip, pickets, piteous, pivot, prettiest, quibus, quickness, richest, rivet, sickness, spinach, spirit, strictest, strictness, syrup, thickets, thickness, ticket, vicious, viscous, vitreous, wicket, witness
3 Syllables: USU
ambitious, amphibious, Archbishop, assiduous, auspicious, bacillus, capricious, deliberate, delicious, elicits, enigmas, exhibits, explicit, eyewitness, factitious, fastidious, fictitious, illicit, implicit, inhibit, insidious, invidious, judicious, malicious, Mauritius, Narcissus, nutritious, officious, perfidious, pernicious, prestigious, prodigious, prohibit, propitious, religious, seditious, severest, sincerest, suspicious, unfitness, utilise
4 Syllables: UUSU
adventitious, avaricious, expeditious, injudicious, irreligious, superstitious, surreptitious, unpropitious, unsuspicious
Found 101 words across 3 groupings. Skipped 19 excess words of a similar stem.