核心
héxīn · HSK 6
core
⚛️ 核 kernel + 心 heart = the core heart of something
核 means kernel or pit (as in a fruit pit), and 心 means heart. Together they form the very center — the nucleus or nub of any matter. hé-xīn sounds a bit like hex-in, as if hexing right into the center.
核 — wood 木 + 亥 (phonetic)
A semantic-phonetic compound: 木 ('wood/tree') gives the meaning, while 亥 supplies the sound. It originally referred to a hard-shelled fruit pit or kernel inside wood/fruit, then extended figuratively to 'core,' 'nucleus,' and in modern usage 'nuclear' (as in atomic nucleus).
心 — pictograph of a heart with chambers and aorta
心 is a pictograph showing a stylized heart, with strokes representing the organ's chambers and the aorta at the top. Originally meaning the physical heart, it broadened to cover mind, feelings, and intentions, since ancient Chinese thought located thinking and emotion in the heart.