aneurysmal

“Aneurysmal dilatation of the acending aorta.”

Aneurysm means dilation. “Aneurysmal dilatation” is redundant, the equivalent of saying “dilated dilatation.” 
rewritten: “Ascending aortic aneurysm.” or “Dilated ascending aorta.”

Origin: 
1650-60;  < Greek aneúrysma  dilation, equivalent to aneurys-  \(variant stem of aneurýnein  to dilate; see an-3, eury-) + -ma  noun suffix