countersign
n.
1590s, from Middle French contresigne, from contre- "against" (see contra-) + signe "sign" (see sign, n.).
〔李〕[counter-=inreturn 回答的；sign n.信号 ⇒→] n. sign or signal in return to another；password 应答信号；口令
〔李〕[counter-=inreturn 回答的；sign n.信号 ⇒→] n. sign or signal in return to another；password 应答信号；口令