完成
かんせい · kansei · JLPT N3 · noun
completion
🏁 完成 = whole + become: something becomes whole, so it is complete
完 means whole or perfect, as in 完全 (kanzen, perfect). 成 means to become or achieve, as in 成功 (seikō, success). Together they mean finished or completed. The reading kan-sei joins kan from 完 and sei from 成.
完 — roof 宀 + yuán 元 (phonetic)
完 is a semantic-phonetic compound: the roof 宀 suggests a house or enclosure, while 元 supplies the sound 'yuán/wán'. Originally it meant a building that was intact or whole, and the sense broadened to 'complete, finish, whole'.
成 — 戊 (halberd/weapon) + 丁 (nail/man)
Originally a pictograph of a halberd or axe-like weapon, suggesting the act of completing a task by force. Over time it shifted from 'to subdue' to the broader meaning 'to accomplish' or 'to become'. The 丁 element inside also hints at the chéng sound.