A better definition of ‘evolution’?
The focus upon definition of term is a rhetorical strategy often employed to confuse the issue, especially by laity when discussing technical matters. Word meaning and use are easily a source of ambiguity, confusion, contradiction and such that the appeal to the dictionary definition is often an appeal to false authority. At the very least it is worth pointing out that aside from etymology and morphology, empirical disputes are not settled by consulting Merriam-Webster.

"Evolution" is a fairly general concept and it can be useful when discussing technicalities to specify "biological evolution".  For example, "water" might mean specifically "H2O" or generally "clear, odorless, tasteless liquid"  or possibly might be used without qualification in distinguishing "potable water" from ocean water, et cetera.

Consider that the definition of term is not so much the pertinent legacy of biological evolution (pace Darwin, Wallace et. alii). The kind of explanation biological evolution uses is it's hallmark. In particular, biological evolution removed teleology (the study of purpose)) from biology.  

For example:

A teleological explanation of biology:
1) This plant is photosynthesizing in order to survive.
2) This plants species is surviving.  

A biologically evolutionary explanation of species:
1) This plant is photosynthesizing
2) Plant species which photosynthesize have an increased likelihood of survival.  

Note that survival is still at play, but the argument is no longer circular. This is not to say that cause has been cited, however, the logical structure of the argument no longer "begs the question"