The character 研究 is formed by combining two separate characters, each contributing to the overall meaning. The first character, 研 (yán), is itself composed of 石 (shí, meaning "stone") and 开 (kāi, meaning "to open"), historically evoking the idea of grinding or polishing jade or stone, a process requiring careful, repeated examination. The second character, 究 (jiū), is composed of 穴 (xué, meaning "cave" or "hole") and 九 (jiǔ, the number nine, often used to signify "extreme" or "depth"), conveying the sense of probing deeply into something. Thus, together as 研究, the compound visually and conceptually represents the idea of "to research" or "to study" through this metaphor of meticulous, repeated investigation and deep, thorough probing into a subject.