We normally hear of wing geometry with dihedral. Most commonly, when speaking of a wing with negative dihedral, we hear the term anhedral. As I recall the prefix "an" indicates "without". On a few rare occasions I have heard knowledgeable aviation people use the terms anhedral for zero up or downward angle and the term "cathedral' for downward angle (negative dihedral). Which is the correct term for negative dihedral?
The correct term established for years is Anhedral and is referred to as such in so many textbooks I have experienced as to be similar to asking if the sky is generally held to be blue; but I will give Roskam's Aircraft Design as at least one source for this assertion because Roskam is a pretty good go-to.
It also so happens that there is a handy bit of Roskam's Aircraft Design on Google books with the relevant passage highlighted here.
Like John, I have never heard "cath-hedral" used in this manner.
The only thing I can think of where "cathedral" is used in a way other than a reference to a large place of christian worship and with an implied subtext of negativity is the term used by certain fringe political activists (the neo-reactionary or "dark enlightenment" movement) to refer to the generally accepted social contract that stands in opposition to their view of reverting society back into some kind of form of what can be broadly termed neo-feudalism with a side order of ethnic nationalism.