- noun a system that transforms a message into an unreadable form with a secret key
Information & Library Science
- noun a system of writing secrets in code
- noun a system of words, letters, numbers or other symbols, which is used to write secret messages.
Origin & History of “cipher”
The central meaning of cipher is ‘zero’ (a word to which it is related); its use since the 16th century in connection with encrypted communications derives from the fact that in their earliest forms such codes usually consisted of numbers representing letters, and cipher had by then broadened in use from ‘nought’ to ‘any numeral’. It entered English through Old French cifre, which came via medieval Latin cifra from Arabic sifr (source of English zero); this was a nominal use of an adjective meaning ‘empty’.