The adjective apocryphal means something that is not true although it is often believed by some people.

Synonyms are fake, fictitious, inaccurate, or questionable.

The word origins in 1580s. It comes from apocrypha meaning “of doubtful authenticity plus –al. In Middle English (late 14th century), aprocrive is used in the same sense.

Everything we heard about her is almost certainly apocryphal.

It is the most popular of all the apocryphal articles for the history of the Earth.

It is an unknown story, but I doubt it is apocryphal.