kateph

This is the plain bodily meaning, and almost every use of it turns on one idea: the shoulder is where a person (or animal) carries a weight. Loads ride on it, the ark and the tabernacle furniture were borne on it, and an idol has to be lifted onto it because, unlike the living God, it cannot move itself.

From that picture the Hebrew builds two natural extensions. First, the priestly vest had two shoulder-pieces, the bands of cloth that sat on the high priest's shoulders and held the stones engraved with Israel's names, so the high priest carried the people before God on his shoulders. Second, because the shoulder is the body part that bears a burden, refusing to bend it became a vivid image for refusing to obey: to give a stubborn shoulder is to shrug off the yoke of God's commands, and to shove with the shoulder is to bully the weak.

These are all one sense at heart, the load-bearing shoulder, seen literally, in the priest's garment, and in everyday figures of speech.

Hebrew, like English, lets the body word travel to things that have a shoulder-like part. A wall, a courtyard, a temple gateway, and a wheeled stand all have a shoulder, meaning a side panel or the flanking section to the right or left of a center.

The same word also names the shoulder of the land: the slope of a hill, the flank that runs down toward a sea, or the side of a nation's territory along a border. Surveyors used it to trace a boundary line as it ran along the shoulder of a ridge, and prophets used it for the exposed flank of an enemy people.

These uses ask for the English word side, flank, or slope rather than shoulder, which is why they form a sense of their own, though the link back to the body is easy to see.