Or search: regress, rational, illation, deduction, inference, synthesis, mentation, prevision, conjecture, prediction, cerebration, anticipation, argumentation, ratiocination
2 Syllables: SU
leverage, realism
3 Syllables: SUU
deepening, equalling, featuring, frequenting, peopling, pyramids, reasoning, seasoning, secreting, secretive, weakening

Found 13 words across 2 groupings.