Relating to or involving controversy or controverted matters; disputed or debated. A rare variant of controversial.
From controversion plus the suffix -al. An archaic or literary form, not standard modern English.
This is an example of how English had multiple ways to say similar things—'controversional' and 'controversial' once coexisted, but 'controversial' won out because it's simpler and more common.
Complete word intelligence in one call. Free tier — 50 lookups/day.