An example is "beforemath" derived from "aftermath", having an understandable meaning but not a commonly accepted word. A back-formation cannot become a ghost word; as a rule it would clash with Skeat's precise definition, which requires that the word forms have "no meaning".
An example is "beforemath," derived from "aftermath," which has an understandable meaning but isn't widely used. A back-formation cannot become a ghost word; according to Skeat, it must be devoid of meaning for it to work.