Can I trivially change a definition still citing the main reference?
If you are using quotation marks, you have to maintain the sense of the original quote, even if you excise or reword elements for clarity in the context of your document.

In this case, it is clear that they are considering only computer systems, so it is not a trivial modification. I would thus say that your options are:


Use the narrower quote, then explain that you are extending beyond computer systems.
Find another quotation source that is more general
Don't use a quote at all in establishing your definition


Personally, I would go with the latter, since reconfiguration isn't a particularly obscure or specialized concept.