Or search: dyspneal, dyspneic, dyspnoeic
4 Syllables: SUUU
deviating, mediating, obviating, permeating, radiating
5 Syllables: USUUU
alleviating, appreciating, appropriating, associating, conciliating, delineating, depreciating, excruciating, humiliating, initiating, negotiating, officiating, repudiating
6 Syllables: UUSUUU
differentiating

Found 19 words across 3 groupings.