Or search: tentative, conditional, probationary, provisionary
2 Syllables: SU
mineral
3 Syllables: SUU
Biblical, clinical, criminal, difficult, digital, integral, liberal, literal, littoral, minimal, miracle, mythical, pinnacle, pitiful, pivotal, syllable, typical, visceral, visible, visual
3 Syllables: USU
peripheral
4 Syllables: SUUU
formidable
4 Syllables: USUU
additional, admissible, conditional, derivable, despicable, divisible, divisional, Episcopal, equivocal, explicable, hospitable, illiberal, invisible, medicinal, municipal, nutritional, occipital, original, permissible, political, pontifical, reciprocal, satirical, traditional, transitional
5 Syllables: UUSUU
aboriginal, inadmissible, individual, inexplicable, inhospitable, irresistible, monosyllables, unconditional, unequivocal

Found 57 words across 6 groupings. Skipped 8 excess words of a similar stem.