自由基

zìyóujī
free radical

CEDICT

Entry Composition

1 自由 zìyóu
  1. freedom; liberty
  2. free; unrestricted
2 基 jī
  1. (bound form) base; foundation
  2. (bound form) radical (chemistry)
  3. (bound form) gay (loanword from English into Cantonese, Jyutping: gei1, followed by orthographic borrowing from Cantonese)