plumb line

A length of string or light rope with a weight (Lat. plumbum, “lead”) attached at one end that, when suspended by the other end, will show a true vertical line. It is used in the construction of any object that needs to be vertically true, such as a wall of a building or a fence. Amos sees the Lord with a plumb line in his hand, which he is using to test Israel. As a result of that test, Israel, for failing to be “plumb” with God, will be destroyed (Amos 7:7-9).