What is the meaning of cypher?

noun

• A mathematical element that when added to another number yields the same number.
  • synonyms: zero, 0, nought, cipher
• 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, cipher, goose egg, naught, zero, zilch, zip, zippo
• A person of no influence.
  • synonyms: cipher, nobody, nonentity
• A secret method of writing.
  • synonyms: cipher, cryptograph, secret code
• A message written in a secret code.
  • synonyms: cipher

verb

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