Wing moment derivative?
 

Hi guys, I'm pretty new to the field of aerodynamics and am reading through some of the literature. As is often the case with these things there's a lot of new jargon I'm not familiar with.

I've looking through graphs of "wing moment derivative" vs Mach number. I'm not sure what a moment derivative is and was hoping someone could explain the term or point me to a reference that would help me understand it.

many thanks, Dave