Where does “副作用” come from?

副作用 (Japanese) comes from Japanese 副, from Middle Chinese 副.

副作用 (Japanese): side effect

Definitions

  1. side effect

Ancestry of “副作用”, step by step

副作用 traces back through two separate lines of ancestry.

via Japanese

StepLanguageWordMeaning
1Japanesecopy; Short for 副詞; assistant, sub-, vice-,...
2Middle Chinese

via Japanese 作用

StepLanguageWordMeaning
1Japanese作用action, operation; effect; function
Every word from Middle Chinese Every word from Japanese
副作用 — Etymology, Origin & Word History | Etymology Explorer