Source : Webster's Revised Unabridged Dictionary (1913)

Cipher \Ci"pher\, v. i. [imp. & p. p. {Ciphered}; p. pr. & vb.
   n. {Ciphering}.]
   To use figures in a mathematical process; to do sums in
   arithmetic.

         ``T was certain he could write and cipher too.
                                                  --Goldsmith.

Cipher \Ci"pher\, v. t.
   1. To write in occult characters.

            His notes he ciphered with Greek characters.
                                                  --Hayward.

   2. To get by ciphering; as, to cipher out the answer.

   3. To decipher. [Obs.] --Shak.

   4. To designate by characters. [Obs.] --Shak.

Cipher \Ci"pher\, n. [OF. cifre zero, F. Chiffre figure (cf. Sp.
   cifra, LL. cifra), fr. Ar. [,c]ifrun, [,c]afrun, empty,
   cipher, zero, fr. [,c]afira to be empty. Cf. {Zero}.]
   1. (Arith.) A character [0] which, standing by itself,
      expresses nothing, but when placed at the right hand of a
      whole number, increases its value tenfold.

   2. One who, or that which, has no weight or influence.

            Here he was a mere cipher.            --W. Irving.

   3. A character in general, as a figure or letter. [Obs.]

            This wisdom began to be written in ciphers and
            characters and letters bearing the forms of
            creatures.                            --Sir W.
                                                  Raleigh.

   4. A combination or interweaving of letters, as the initials
      of a name; a device; a monogram; as, a painter's cipher,
      an engraver's cipher, etc. The cut represents the initials
      N. W.

   5. A private alphabet, system of characters, or other mode of
      writing, contrived for the safe transmission of secrets;
      also, a writing in such characters.

            His father . . . engaged him when he was very young
            to write all his letters to England in cipher. --Bp.
                                                  Burnet.

   {Cipher key}, a key to assist in reading writings in cipher.

Cipher \Ci"pher\, a.
   Of the nature of a cipher; of no weight or influence.
   ``Twelve cipher bishops.'' --Milton.

Source : WordNet®

cipher
     n 1: a message written in a secret code [syn: {cypher}]
     2: a mathematical element that when added to another number
        yields the same number [syn: {zero}, {0}, {nought}, {cypher}]
     3: a quantity of no importance; "it looked like nothing I had
        ever seen before"; "reduced to nil all the work we had
        done"; "we racked up a pathetic goose egg"; "it was all
        for naught"; "I didn't hear zilch about it" [syn: {nothing},
         {nil}, {nix}, {nada}, {null}, {aught}, {cypher}, {goose
        egg}, {naught}, {zero}, {zilch}, {zip}]
     4: a person of no influence [syn: {cypher}, {nobody}, {nonentity}]
     5: a secret method of writing [syn: {cypher}, {cryptograph}, {secret
        code}]
     v 1: convert ordinary language into code; "We should encode the
          message for security reasons" [syn: {encode}, {code}, {encipher},
           {cypher}, {encrypt}, {inscribe}, {write in code}] [ant:
           {decode}]
     2: make a mathematical calculation or computation [syn: {calculate},
         {cypher}, {compute}, {work out}, {reckon}, {figure}]