Meta and supersets / subsets.

Basically, if A is a superset of B, then B is a subset of A.
If "a superset of" is substituted with meta such that A is meta B,
what would the substitution of "a subset of" be?
I was looking around as to where the prefix meta- got its popularity
and according to the Wikpedia page for the prefix, you appear to be
the source.
Or is meta- a one-way superset tag with no matching subset?