a target: the mark something is aimed at and shot at
The word names the fixed point that an arrow is aimed at. Its one everyday use is part of a coded signal: Jonathan tells David he will shoot three arrows off to the side of David's hiding place, as though he were aiming at a mark, so that what David really has to watch is where the boy is sent to fetch them.
Twice the picture is turned on a person, and both times the archer is God. Job says he had been living at ease when God took him by the neck, shook him to pieces, and then stood him up as a target. The poet of Lamentations says God bent the bow and set him as the mark for the arrow. What stings in both is not the wound but the aim: an archer chooses what to shoot at, so the suffering cannot be brushed off as an accident.
This same word carries a second meaning, a guard post, and the two probably meet in the idea of a fixed gaze. The verb they both grow from (נָטַר) means to keep or watch over something. A guard is someone whose eyes stay on a place; a target is the thing eyes stay on. Nothing in these three verses depends on that link, and no passage in the Bible plays on the double sense.