Give it a name which exists as an English word.

The OED has recorded 'steganography' from 1569 to 1823, but not since, and classes it as 'obsolete'. "Steganogram" appears as late as 1904, which can hardly be regarded as current. The present name may provoke interest, and convey a meaning to a specialised group, but to the vast majority of people it conveys nothing. I would not have thought that this was in the best interests of communication, or even of advertising.