Can I trivially change a definition still citing the main reference? I am going to directly use the following definition of reconfiguration (as a quotation) from A Dictionary of Computing as follows.


  The process of redefining and in some cases reconnecting the units of
  a multiple-unit computer system. This procedure may be accomplished
  automatically, manually, or by a combination of both. The purpose may
  be to provide different system functionality or continued operation
  after the failure of one unit. If done automatically the latter case
  would represent a fail-soft situation. See also configuration.


However, this definition only considers computer systems. So, I need a more general version of the definition referring to all kinds of systems. To fix the issue, am I authorized to simply eliminate that computer word in the definition and still citing the source dictionary?
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.