Translating into coded form.
To encipher is to take a piece of information or a message and translate it into a coded form. You can encipher a note to your friend by replacing the letters with specific numbers.
If your friend enciphers an email before sending it, you’ll need to know what code they used before you can decipher it and read it. A simple way to encipher language is to replace A with 1, B with 2, and so on. Originally, cipher meant “do arithmetic,” from the Arabic root sifr, “zero,” and because coding with numbers was so common, ciphercame to mean “write in code.”