交差
こうさ · kousa · JLPT N2 · noun
cross
✖️ 交 (kou) = intersect, 差 (sa) = difference: lines that differ in direction and meet = cross
交 means to mingle or meet, and 差 means to diverge or differ. Together they describe two lines that diverge and then meet, forming a cross.
交 — top 亠 + 父-like crossed legs
Originally a pictograph of a person standing with legs crossed, showing the idea of crossing or intersecting. From this concrete image, the meaning extended to abstract senses like 'exchange,' 'interact,' and 'hand over.' Modern uses such as 交流 (exchange) and 交通 (traffic) all trace back to this core notion of crossing.
差 — 垂 (drooping) + 工 (work/tool)
Originally depicted a hand reaching down to grasp grain stalks of uneven length, suggesting discrepancy or unevenness. From this came the meaning 'difference' or 'to differ.' The reading chā specifically carries the sense of disparity, while other readings developed meanings like 'to dispatch' (chāi) and 'poor/lacking' (chà).