When we write, we are trying to give voice to our thoughts--to put the ideas into words. Thus the words we are using represent our thoughts. And these words may not always fit. Sometimes we'll look for a word and find none that seem to suit us. do we then stop? Do we then give up and say "I can't find the word, therefore I must not have anything to say"? That would be one way of going about it. But frequently we use a word that is the best fit that we can find.
Now there may be sticklers out there who insist that a word means just what it means in the dictionary, but realistically, all writers do some definition of their own terms. We find words whose meaning is close enough, and we use them in a way that suits our work.
As writers we can then take time to define the term as we are using it. Such a definition may need to include some acknowledgment of other ways of using the word--especially uses of the words that are common in the discourse of your field.
By saying how we are using a term, and by explaining to our reader the usage we intend we are writing as responsible academic writers. This is a perfectly normal part of academic writing. This is even true if we want to use a term that might conflate some distinctions: we can, in defining our term, acknowledge the distinctions that we are cutting out of our discussion, and in so doing, both responsibly acknowledge complexity that exists in the discourse and at the same time keep our work focused on the material that is of greatest significance to us.
Definition can be a rabbit hole--there's a whole world to explore in the attempt to define a term. Each sentence we put forward in our definition can be seen as requiring its own explanation. When we try to incorporate all the different voices that have used a term and try to discuss the distinctions, we take on a project that is of massive scope--almost independent of the term that you wish to define. If we believe that words are meaningful in terms of their context (e.g., Charles Fillmore's theory of Semantic Frames), then different world views will often lead to different meanings of a word--even when the same or similar words are used in the definition--the underlying understanding of the world that shapes definition, means that the possible subtle (or not-so-subtle) definitions of different people will not match or mesh perfectly, and each attempted definition becomes embroiled in the need to explain a whole world view.
Sometimes definition can be relatively straightforward, but that's not usually the case for the terms we have to define. When writing, it's important to take the initiative on this sort of point: don't let yourself get bogged down in endless discussion of what the word can and does mean in other places and to other authors; focus on what the word means to you.
Here's the quote from an e-mail I sent to writer this morning who was dealing with the difficulty of pleasing an advisor with respect to a number of different terms that share close similarities, but also have distinctions:
Re: Terminology. I like to try to define my own terms and tell the reader "yes, I know that there are other ways to talk about this, and yes, I know that I may be conflating some theories that have important distinctions, and yes, I know I may be ignoring other theories that have important similarities, but for this paper, and for my work, I am defining the term in this general way, and may use similar terms as synonyms." The thing is, that if you really want to define terminology, that can be a huge rabbit hole: definition is problematic, and clearly distinguishing the subtle yet important differences between similar ideas can be time-consuming. If instead you head the reader off by saying "This is my usage, and I'm sensitive to other usages, but I'm still going to use the term this way," Then you can show the reader that you're sensitive to the important distinctions without being burdened by continual need to redefine terms, or to define new ones.
Generally speaking, by taking charge of the discussion and saying to the reader, "Yes, I see this alternate path to follow, but my choice is to continue down the path I was already on," the author shapes the reader's response by revealing both scholarship and a reasoned set of choices that guided construction of the work. A reader will generally feel more comfortable reading if he or she has the sense that the writer actually has a destination in mind.