Flection and Knife-edge

Flection noun - The state of being flexed (as of a joint).

Knife-edge and flection are semantically related in fold topic. In some cases you can use "Knife-edge" instead a noun "Flection", when it comes to topics like double thickness.

Knife-edge noun - A narrow boundary.

Flection and knife-edge are semantically related in fold topic. You can use "Flection" instead a noun phrase "Knife-edge", if it concerns topics such as double thickness.