The word 核心 is formed by combining two characters, each contributing a layer of concrete imagery to create an abstract concept. The first character, 核, originally depicts the hard, central seed or pit of a fruit, the indispensable core from which life grows. It is paired with 心, meaning "heart", the vital, central organ of the body and the traditional Chinese seat of thought and emotion. Together, they create a powerful compound metaphor: just as a seed is to a fruit and a heart is to a body, the 核心 represents the absolute essential center, the foundational and most critical part of any system, idea, or organization.