Jam-up and Monkey wrench

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

Monkey wrench and jam-up are semantically related. in obstruction topic. In some cases you can use "Monkey wrench" instead a noun phrase "Jam-up".

Monkey wrench noun - Adjustable wrench that has one fixed and one adjustable jaw.

Jam-up and monkey wrench are semantically related. Sometimes you can use "Jam-up" instead a noun phrase "Monkey wrench".