Garble

1. An error in transmission, reception, encryption, or decryption that changes the text of a message or any portion thereof in such a manner that it is incorrect or undecryptable.

2. In a telephone circuit or channel, readily audible but unintelligible interference from another circuit or channel.

Note: Garble may, for example, take place in an FDM telephone carrier system in which an interfering signal from another channel or system is demodulated in such a fashion that it has an objectionable audio power level but is nonetheless unintelligible.

Source: from Federal Standard 1037C and from the Department of Defense Dictionary of Military and Associated Terms