Or search: dentistry, fastening, soldering, technique, attachment, odontology
2 Syllables: SU
awning, bombing, Brahmin, calming, dawning, fawning, flaunting, haunting, launching, longing, prompting, taunting, thronging, Unwin, wanting, yawning
3 Syllables: USU
belonging, desponding, prolonging, responding
4 Syllables: UUSU
corresponding

Found 21 words across 3 groupings. Skipped 4 excess words of a similar stem.