Or search: usa, u.s., tiro, tyro, newbie, novice, entrant, fresher, recruit, starter, beginner, enlistee, initiate, neophyte, newcomer
2 Syllables: SU
blessing, deafening, destined, dredging, Dresden, dressing, edging, etching, fetching, guessing, jesting, Lessing, leveling, Levin, nesting, nestling, pledging, pressing, resin, resting, sketching, stressing, stretching, testing, threshing, vesting, wresting, wrestling
3 Syllables: SUU
digesting, protesting
3 Syllables: USU
addressing, alleging, arresting, assessing, attesting, caressing, clandestine, compressing, confessing, contesting, depressing, distressing, endeavoring, expressing, impressing, investing, oppressing, possessing, professing, progressing, refreshing, repressing, requesting, suggesting, suppressing, transgressing, undressing
4 Syllables: UUSU
prepossessing

Found 58 words across 4 groupings. Skipped 4 excess words of a similar stem.