Hello!
 
Hi to all,
 
Definitions from dictionaries typically "don't fit" when it comes
to evolutionary biology, population genetics etc etc.
Most evolutionary terms are concepts and should be understood rather
than "Clintonized" with a dictionary or other cut/dry definitions.
 
As a suggestion there are many books (NOT sorry textbooks) addressing
these concepts, as an example, but not all, by any means;
 
The Extended Phenotype by Dawkins has a chapter "An Agony in Five Fits"
discussing at length five different concepts of "fitness" in the
evolutionary sense.
 
Darwin's Dangerous Idea by Dennet looks at "fitness" from the
philosophical sense.
 
Reinventing Darwin by Eldredge also addresses "fitness" from
his "punctuated" point of view.
 
On and on, there are many ways of conceptualizing "fitness"
post Darwin.
 
Later,
 
Emilio Jorge Power