(qaw, qeweh): The usual meaning is simply line, rope or cord, in Isa 28:10,13, but the line was used for measurement, as is evident from such passages as 1Ki 7:23; Job 38:5; Jer 31:39. Whether the line for measuring had a definite length or not we have no means of knowing. In Isa 44:13 it refers to the line used by the carpenter in marking the timber on which he is working, and in Zec 1:16 it refers to the builder's line.
Figuratively: It signifies destruction, or a portion of something marked off by line for destruction, as in 2Ki 21:13; or for judgment, as in Isa 28:17.
H. Porter