Being a native German speaker, I just came across the word "Rhenish" (as a translation of German "rheinisch", belonging to the Rhine).
I am a bit confused about this, and am at a loss for the proper "language words" to describe it... I have long since ceased to think about either German or English in grammatical terms, going by "feel", and it's just not clicking here.
The German transformation from Rhein to rheinisch follows the "usual" pattern for such transformations (e.g. Logik -> logisch).
But the English transformation from Rhine to Rhenish "feels" awkward, and the result looks like a rather mangled attempt to spell the German rheinisch. The dropped / missing "i" looks especially weird. Going with my "gut feeling" I would have expected something like rhineish...?
Sorry for not being able to put my finger on it, but... can somebody explain what is "going on" here with Rhine -> Rhenish?