症结
zhēng jié · HSK 7
crux of an issue
🪢 症 (illness) + 结 (knot) = an illness-knot: the tangled crux or sticking point of a problem
Literally a hard knot/lump in the abdomen in Chinese medicine. 结 means to tie or knot (same as in 打结, tie a knot), so 症结 extended to mean the knotty core issue, the crux of an argument or the sticking point holding things up.
结 — silk radical 糸 + lucky 吉 (phonetic)
结 is a semantic-phonetic compound. The silk radical 糸 on the left signals the meaning, since the original sense was tying threads or cords into knots. The right side 吉 (jí) provides the sound. From the literal 'knot' it extended to figurative senses like 'bind,' 'conclude,' or 'form (a bond).'