Meta-ethnicity is a relatively recent term (or neologism) that arises occasionally in academic literature or public discourse, and when it does, seems to be an attempt to describe a level of commonality that is wider and more general (i.e., might differ on specifics) than ethnicity, but does not necessarily correspond to (and may actually transcend) nation or nationality.
"Against this dominant view of the nature of the Indian state, Singh argues that India should be seen as an 'ethnic democracy' in which Hinduism works as a meta-ethnicity and in which hegemonic control is exercised over ethnic minorities, particularly those living in the peripheral regions."
"We also know that demographically by the year 2050 less than one in two Americans will be a white Euro-American. There has even been talk of a kind of meta-ethnicity or post-ethnicity. That is to say that intermarriage, mix, birth-rate, etc. will lead to not one, nor two or even three ethnicities feeding into people’s make-up, but many more."
"L. Byzov, however, believes that 'there has taken place within the Russian national consciousness one of the most radical changes ever: from a meta-ethnic sense of identity to a strictly ethnic identity' (Byzov 1996, 45)."