Question

The ability of an organism to survive and reproduce in its environment is called its

Answer 1

To survive and reproduce, all living organisms must adjust to conditions imposed on them by their environments. An organism's environment includes everything impinging upon it, as well as everything that is affected by that organism. Conformity between an organism and its environment constitutes what biologists call adaptation.

http://www.biologyreference.com/A-Ar/Adaptation.html

Answer 2

Actually, I'd say it's "fitness", as adaptation is more about adapting to environmental changes, than the survival and reproduction.
but I guess it really is just two different ways of saying it !