cipher, cypher -- (a message written in a secret code)
zero, 0, nought, cipher, cypher -- (a mathematical element that when added to another number yields the same number)
nothing, nil, nix, nada, null, aught, cipher, cypher, goose egg, naught, zero, zilch, zip, zippo -- (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")