加工
かこう · kakou · JLPT N1 · noun
fabrication
🏭 加工 = 加 (add) + 工 (work): adding work to raw material = processing
加 means add or apply, and 工 means work or craft. Manufacturing and treatment both mean adding work to raw material to make something new. 工 also appears in 工場 (factory).
加 — force 力 + mouth 口
加 is traditionally analyzed as a compound of 力 (strength) and 口 (mouth), suggesting boasting or exaggerating one's effort with words. From this it extended to the meaning 'to add' or 'increase'. Today it is used broadly for addition, both literal and figurative.