One was a discussion of the term "anarchist" by an anarchist friend of mine who complains that the term is used "wrongly" by those who use it as a popular term for those opposing any government. Of course, that is one meaning of the word, and a more common one than his preferred use of the word "anarchist", which is a political theory where a government does not use force, but is instead replaced by a voluntary cooperative society.
In a forum about theology, I had a discussion about the word "Christian" and if it means a "real" disciple of Jesus or just someone who goes to church. Some claimed that since the Bible three times uses the word "Christian" for disciple, that they mean the same thing.
I think that both of these folks are supporting a fallacy about words: that they are static, have one primary meaning and that primary meaning is the "real" meaning and other uses of the word are "wrong." What we need to recognize that besides homophones, words generally do not have a single, concrete meaning, but a range of meanings, which linguists call "semantic categories." A word is not a sign, which will remain in one place, never changing, but rather a pool ball, bouncing around within a limited context. The meaning in any sentence depends on the other pool balls, and we need to see where it lands.
Even so, to speak of "anarchists" negatively isn't wrong, it is just using the word in one of the appropriate meanings. Those who classify themselves as "anarchists" politically might want to think about using a new term unless they want someone to assume something different than they intend.
In this way, I do not use the word "Christian" as if that is what saves someone. No matter how it is used in the Bible, "Christian" is more commonly known as someone who associates oneself to the social world of Christianity, not necessarily a committed, faithful disciple. So I'd rather use the term Christian for how it is meant in the majority of the world-- a social label. And for those who recognize that Jesus is Lord, I'd rather say "follower of Christ." I don't have a problem with people using "Christian" in a narrow sense. I think it's just less confusing in most contexts not to use it that way.
If you are interested in reading about ranges of meaning for words, here are a couple articles:
The Living Word by Peter Ludlow
Word Senses and Taxonomies