Passcode and Cipher

• (n.) 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.
• (n.) A character in general, as a figure or letter.
• (n.) A private alphabet, system of characters or other mode of writing, contrived for the safe transmission of secrets; also, a writing in such characters.
• (v.t.) To decipher.
• (v.i.) To use figures in a mathematical process; to do sums in arithmetic.
• (a.) Of the nature of a cipher; of no weight or influence.
• (v.t.) To get by ciphering; as, to cipher out the answer.
• (v.t.) To designate by characters.
• (n.) A character [0] which, standing by itself, expresses nothing, but when placed at the right hand of a whole number, increases its value tenfold.
• (v.t.) To write in occult characters.
• (n.) One who or that which, has no weight or influence.

noun

• A message written in a secret code.
  • synonyms: cypher
• A mathematical element that when added to another number yields the same number.
  • synonyms: zero, 0, nought, cypher
• A quantity of no importance.
  • usage: "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"
  • synonyms: nothing, nil, nix, nada, null, aught, cypher, goose egg, naught, zero, zilch, zip, zippo
• A person of no influence.
  • synonyms: cypher, nobody, nonentity
• A secret method of writing.
  • synonyms: cypher, cryptograph, secret code

verb

• Convert ordinary language into code.
  • usage: "We should encode the message for security reasons"
  • synonyms: code, encipher, cypher, encrypt, inscribe, write in code
• Make a mathematical calculation or computation.
  • synonyms: calculate, cypher, compute, work out, reckon, figure

(DoD) Any cryptographic system in which arbitrary symbols (or groups of symbols) represent units of plain text of regular length, usually single letters; units of plain text are rearranged; or both, in accordance with certain predetermined rules. See also cryptosystem.