secret code

English Thesaurus

1. a secret method of writing (noun.communication)

hypernym	:	code,
definition	:	a coding system used for transmitting messages requiring brevity or secrecy (noun.communication)

derivation	:	cipher, code, cypher, encipher, encrypt, inscribe, write in code,
definition	:	convert ordinary language into code (verb.communication)

derivation	:	cipher, code, cypher, encipher, encrypt, inscribe, write in code,
definition	:	convert ordinary language into code (verb.communication)