硏

Phono-semantic compound:

石 (석, “stone”) — semantic component, indicating relation to stone or grinding.

幵 (견, “flat, level”) — phonetic component, lending the sound -연 / -yan.

Originally depicted the action of rubbing or grinding stone tools. From this, extended to mean:

- grinding an ink stick on an inkstone, hence “inkstone” itself,

- figuratively, polishing and refining one’s learning, leading to “study, research.”

硏究 (연구) — research, study

硏磨 (연마) — to polish, hone, refine

硏究所 (연구소) — research institute

硏覈 (연핵) — to investigate thoroughly

Korean: 연 (common in academic/technical terms like 연구).

Simplification: In Mainland China, the form 研 is standard. 硏 remains used in Korea (esp. in Hanja contexts).

The metaphorical shift “to grind/polish” → “to study diligently” is parallel to English “to polish one’s skills.”