Jam-up and Knife edge

Jam-up noun - A crowded mass (as of cars) that impedes or blocks movement.

Knife edge and jam-up are semantically related. In some cases you can use "Knife edge" instead a noun phrase "Jam-up".

Knife edge noun - The sharp cutting side of the blade of a knife.

Jam-up and knife edge are semantically related. Sometimes you can use "Jam-up" instead a noun phrase "Knife edge".