There are two ways that words can come to have meaning--common use and stipulation.
Most words we use in every day life get their meaning through common use. Unless we invested our words with meaning by having an intention behind them when we use them, they would just be arbitrary sounds, scribblings, or gestures we made. It is because there is a thought or intention behind the words that they have meaning to us. Effective communication depends on everybody using words in the same ways. It's through interacting with people that common use takes place.
Language changes over time and can be different from place to place. That's because words can take on new meaning as people begin to use them in different ways. And if people are isolated from each other, they can take their language in a different direction. Eventually, they can become so different that they are different languages altogether.
Since language grows organically, it can be a rough process. It's inevitable that while a group of people are ironing out precise meanings to their words, there's going to be some conflict and misunderstanding along the way. If two people use the same words but with slightly different meanings, they will have a miscommunication. Sometimes miscommunication can happen without either person realizing it.
Sometimes, in the process of ironing out the meaning of words, we resolve conflict by accepting that each word can have more than one meaning. To understand each other in those situations, we have to rely on signs, the most important of which is context. The fact that words can have more than one meaning (since they are used in more than one way) can result in mistakes in reasoning. For example, if we use the same word with two different meanings, but treat them as if they refer to the same thing, then we can commit the fallacy of equivocation. People commit this fallacy sometimes on accident because they aren't thinking carefully enough about what they are dealing with. But people can also exploit equivocation to deceive and manipulate. People can also exploit equivocation to make a joke.
Dictionaries exist for the purpose of capturing the various uses of words. A good dictionary will put the most common use at the top. It's important to note that dictionaries don't give words their meaning; rather, they try to accurately capture the meaning they already have through common use. The definition a dictionary gives is only "correct" insofar as it accurately captures how people use words. A dictionary isn't right just because it's the dictionary. It's not right by definition, in other words. A dictionary can even be wrong if it fails to capture how words are used.
Words can also get their meaning through stipulation. We often use dictionaries in this way. While they are originally written to capture the common uses of words, a dictionary can carry authority if we're all willing to grant it authority. Then we can use the dictionary to settle disputes about the meaning of words. We treat the dictionary as if it's correct by definition. This can have some practical advantages.
When words get their meaning through stipulation, it most often happens when words are being used as terms of art. So, for example, if you're a physicist, an historian, a philosopher, a painter, or whatever, you might have particular words that are used in those fields with meanings that are peculiar to those fields. The meaning of those words in those contexts may be quite different than common use.
When somebody writes a paper in some specialized field or subject, they will sometimes either invent a word or use a word with some particular meaning that may differ from common use. If it's a good paper, and the author intends to use a word in a particular way that may be different than common use, they will be careful to define the word in their paper so the reader knows precisely what they mean by it. It could be that the definition they give is "wrong" according to common use, but that shouldn't matter. As a matter of praticality, all that should matter is that the reader knows what the author means.
The reason I'm belaboring all these points is because I see language causing a lot of unnecessary conflict between people, and I want to offer some suggestions for avoiding that conflict.
Conflict can happen when there's a misunderstanding between people. While most of us can agree that we should all define our terms so as to avoid miscommunication, we don't always know what terms need defining and which can just be taken for granted. So in spite of our best efforts at avoiding misunderstanding, it's still going to happen. The solution is not to accuse somebody of being deceptive or inconsistent, but to ask them what they mean. If it turns out that whatever meaning they tell you is not the most broadly accepted meaning of that word, the solution is not to correct them and tell them that's not what the word means. The solution, instead, is to interpret what they are saying in light of how they are using that word. That's the more amiable way of dealing with people.
If you treat language pragmatically, there's no reason to get up in arms with somebody over what you perceive to be the wrong use of a word. Arguing over the meaning of words is pointless if the bottom line is just to understand what each other are saying. The pragmatic approach is to listen to each other, ask each other what you mean, and interpret what they say in light of the definitions they give you.
There are times when it's useful to argue over the meaning of words, though. When two people are trying to interpret a third person (especially when that third person is long dead and left some writing behind), it's useful for the two people to argue over what the third person meant by their words since that deterimines the correct interpretation.
It can also be useful to argue over the meaning of words when it seems like they are being used in equivocal ways. This is especially the case when a word can carry a negative connotation but doesn't have to. Imagine this conversation:
Jim: Bob, you are a BLANK (used with a negative connotation).
Bob: Yes, I am a BLANK (used without a negative connotation).
Jim: Oh, did y'all hear that? Bob just admitted that he's a BLANK (used with a negative connotation).
Bob: Well, no, I'm not a BLANK like that. [picking up on Jim's negative meaning]
Jim: Oh, don't backpeddal now, you just admitted it. [Jim exploiting the equivocation in a dishonest way and treating Bob uncharitably].
Bob: When I said I was a BLANK, I didn't mean it the way you're using it.
Jim: But my definition is correct.
I suppose some people mean to engage in conflict when they try to stick somebody with whatever negative connotation a word might carry. If they can get the person to admit to owning that word, even if in a benign sense, then they exploit the opportunity to treat the person as if they've just admitted to something nefarious. In the cases like that, it makes good sense for a person to defend themselves by arguing over the meaning of a word. It's a shame one must do this, though.
