Secret code
01
秘密代码, 密码
a private system of symbols or words that represents a message known only to the sender and recipient
例子
The spy used a secret code to send the message.
间谍使用了一个秘密代码来发送消息。
They cracked the secret code hidden in the letter.
他们破解了隐藏在信件中的密码。
