finnage means fins on something such as a fish. Lexicurio rates it Sui generis — a strength score of 87 out of 100.
Etymology
From fin + -age.
noun
- fins on something such as a fish.“A good Platy should have a deep body, well spread finnage, and bold colour; for example, Red Platies must have a scarlet-red body with the red spreading into the fins. They should not be of the pinky orange shade which we so often see.”