What is mean by compounding variable?

I think there is confusion between the terms "compounding variable" and "confounding variable".

My way of looking at it is that compounding variables describe elements of mathematical functions, only. Confounding variables apply to any research in any domain and are external variables to the research design which might impact on the dependent variable to a lesser or greater extent than the independent variable, which are part of the research design.

I am Peter Davies at classmeasures@aol.com