I've always had a thing for literature older than me. I didn't have much interest in "Nancy Drew" or the "Hardy Boys." Instead, I grew up reading the "Trixie Belden" and "Cherry Ames" books that my mom had read growing up. I, of course, loved the "Lord of the Rings" and the "Chronicles of Narnia" series. "Sherlock Holmes?" Brilliant. I devoured the "Iliad" (boring) and the "Odyssey" (hilarious) in elementary school.
Even most of the “modern” authors I like are older. "Redwall" was my obsession at the beginning of second grade and lasting through much of middle school. "Shannara" is one of my favorite fantasy series, along with the "Magician" series by Feist. Mercedes Lackey, Robin McKinley, Dianna Wynn Jones and Terry Pratchett all have spots of honor on my bookshelves.
All of these writers have written, at one point or another, during a time in which certain parts of language meant something different than they do now. This fact actually caused some problems for me as just a reader, long before it had any effect on my writing.
One of my most solid memories of elementary school is getting in trouble for saying I was gay. At the time, homosexuality wasn't as discussed as it is today. I had never heard the word gay used in that way, and only knew it from my books as meaning “happy." A couple of kids started harassing me for it, though I didn't know why, and it eventually got reported to an adult who explained things to me.
I thought it was stupid at the time, and a part of me still is irked by it today. Why shouldn't I use a word whose definition had meant one thing for a very long time, simply because it had been commandeered to also mean another thing?
Another example about language change from my personal life comes thanks to my mom. She kept a strict “No foul language” rule on our house. However, what my mom considered a bad word was rather more inflexible than in many other households. The word I remember us having problems with the most was “sucks."
Now, to my generation, to say something sucks is to mean that it isn't good. To my parents, it had begun as a word meaning something being pulled in a direction by a power outside of its control. My mom's problem with the word came from the sexual connotations that had begun to accompany it somewhere in between the two generations, and the fact that kids who didn't actually curse were using it as a substitute cuss word.
Unfortunately, it was the preferred word of choice for one of my cousins. In his own house (not having the same rules), he would frequently exclaim that something sucked whenever he was over at our house. It was a hard habit for him to break, and he couldn't fully understand why my mom wanted him to quit saying it. He found a loophole; instead of saying something sucked, he would say it “inhaled profusely." (Even now, my 30-year-old cousin still uses this expression from time to time.)
The point of all of this is to point out that different words can have different meanings for different people. The examples I've given have all been from one culture–now imagine the even more drastic differences between multiple cultures. (My dad's favorite example for this would likely be taco salad. Having grown up near the border to Mexico, I automatically think of a corn tortilla with fillings, accompanied by greens. In Japan, however, a taco salad is a squid dish.)
As an author, these are things which I have to ponder when I'm writing something. There are times where I know exactly what I want to say, and I have just the words to say it in. However, will those words mean the same thing to my readers as they do to me?
If I talk about hearth, most people a generation or two above me will know what I mean. However, that word might mean something different to people who own a fireplace, but don't know the old connotation of the word. People who don't fit into either category could not have a clue what I'm talking about.
One of my beta readers was somewhat confused when looking through my second book. One of my characters worked at the Ren Faire, which I called by that name. It's the most common term for the event in southern Arizona, and since he had grown up here the same as I had I assumed he'd know it. However, when I got the book back from him I found little notes and questions next to every mention I made of the Ren Faire. He didn't know what it was. It wasn't until I contacted him and explained that it was short for the Renaissance Festival that he understood. A simple difference, but one that left him with no idea what I was talking about.
Words and their meanings will continue to change, and it's up to the writers to keep up with those changes. It can be challenging at times, but it can also be fascinating to stop and think about how a reader might view something you write completely differently than you intended when you wrote it simply because of a different interpretation of one or two words.