Which term describes a nail that is folded?

A nail that is described as "folded" is referred to as a plicatured nail. This condition features a notable bending or curling of the nail plate, which can create the appearance of the nail being folded over. Such a nail may occur due to various reasons, including trauma or a response to certain health conditions, but the defining characteristic is that it does not lie flat or grow straight like a typical nail.

Ridged nails, on the other hand, are characterized by vertical or horizontal ridges along the nail surface, indicating a different kind of issue. Onycholysis refers to the separation of the nail from the nail bed, which does not imply any folding but rather a lifting. Nail pterygium is a condition involving the growth of skin over the nail bed and does not describe a folding of the nail itself.

Therefore, the term that accurately represents a nail that is folded would be plicatured nail.