交替
こうたい · koutai · JLPT N2 · noun
change
交替 = 交 (cross, exchange) + 替 (replace, take over): things crossing and taking each other's place, like alternating shifts that bring relief
Change happens when one thing crosses over and replaces another. Taking turns (alternating) gives relief, which is why the word also means relief.
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.
替 — two 夫 (man) over 曰 (say)
Originally written with two 立 (stand) over 白, depicting two people side by side, suggesting replacement or alternation. The form evolved to two 夫 over 曰. The core meaning shifted from 'decline/abolish' to 'replace, substitute for'.