Here’s a paper that goes into the many definitions of green infrastructure across different disciplines, along with related concepts. I’ve certainly seen narrow definitions used in my own discipline of water resources engineering. Defining clearly what you mean by a term and sticking to that definition is actually a good thing, because it takes the power out of the words in the definition itself, and you are now defining the actual structure and/or function of something, and you can now have a conversation with someone else once they understand the definition you are using. Using words without a clear definition, or not being aware of alternate definitions or broader perspectives that are out there, is a problem, and unfortunately not an uncommon one.