What this suffix does
-set forms compound adjectives that describe how something is positioned, embedded, or established — the depth and manner of its placement. Deep-set, close-set, well-set, hard-set — each compound describes a quality of position or disposition. "Deep-set" is the most important figuratively: applied to eyes it describes a physical feature; applied to beliefs, habits, and problems it describes how profoundly something is embedded in the structure of a person, institution, or system. These compounds bridge the physical and psychological registers with unusual elegance.