Sphalm is an archaic and largely obsolete word that refers to a 'bad idea', most often a misinterpretation of a religious text, and in practice, an error in a translation or interpretation of the Greek manuscripts containing the oldest texts of the Christian Bible.
Σφάλμα or sphalma was used in Greek to mean a typo or translation error, and this meaning carried over into both Latin and English. It is also obsolete, and is seen most often these days in the Latin phrase sphalma typographicum.
Erroneous doctrines may also be called cacodoxy, heterodoxy, or, most often, heresy.