The biological definition of 'parastatics' is closest to the general one: relating to mimicry between adjacent species. There is likewise a systems definition regarding one system compensating for a weakness in another. And there is a genetic definition. The noun is also used: 'parastasis'.
I first noticed the term in a 60-year-old Polish text (parastatyce) where the reference is to relativity or the quantum.
But although I see the term in physics and math-for-physics abstracts (for example) I cannot find a definition. Google search is somewhat 'contaminated' by the presence of a band of this name. (Just as: searchers for data on 'ceramite' will have to negotiate endless references to a fantasticated material of the same name in a certain gaming universe. Plus what seems to be a trademark issue.)