cipher: [14] 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’. => zero[cipher etymology, cipher origin, 英语词源]