Definitions

ridge; crest; apex

Etymology

The spine  of a mountain  range;  also provides the pronunciation

About

is a phono-semantic compound: the radical (mountain) places it in the domain of topography, while the component (spine) provides the pronunciation jǐ and evokes a ridge or backbone. The character thus denotes the crest or ridge of a mountain range, drawing a direct analogy to an animal's spine. It is a specialized geological term with no extended metaphorical meanings.