Where does “信号” come from?

信号 (Japanese) comes from Japanese 信, from Middle Chinese 信.

信号 (Japanese): a signal; traffic lights

Definitions

  1. a signal; traffic lights

Ancestry of “信号”, step by step

信号 traces back through two separate lines of ancestry.

via Japanese 信

StepLanguageWordMeaning
1Japanese信trust, faith
2Middle Chinese信—

via Japanese 号

StepLanguageWordMeaning
1Japanese号number
2Middle Chinese號—

Words derived from “信号”

Every word from Middle Chinese 信 →Every word from Japanese 信 →
信号 — Etymology, Origin & Word History | Etymology Explorer