Knife-edge and Point of no return

Knife-edge noun - A narrow boundary.

Point of no return and knife-edge are semantically related. In some cases you can use "Point of no return" instead a noun phrase "Knife-edge".

Point of no return noun - A line that when crossed permits of no return and typically results in irrevocable commitment.

Knife-edge and point of no return are semantically related. Sometimes you can use "Knife-edge" instead a noun phrase "Point of no return".