I love words. The editor in me loves the part where I go through the dictionary checking a word is spelled correctly, is being used correctly. The writer loves to wallow in the sounds of words, the rhythms. Both parts combine to form the me who likes to preserve the little differences between words, who loathes the fact that words shift in meaning, often because people don't use them correctly.
Here are some that come up for me regularly. My number one bugbear is the difference between "disinterested" and "uninterested". For the purists (like me) "disinterested" is "unbiased", so you want a disinterested umpire in charge of your cricket match. But many writers use it when they mean "uninterested" (not interested), and, yes, it's been used so much so that the meaning is shifting and "not interested" is now being listed in the latest edition of the Macquarie as one of the meanings of "disinterested". I hate that. Truly. It bugs me that professional writers don't use this correctly. One of my favourite writers does it all the time, and it makes me want to throw her books across the room. Over the top, perhaps, but it really inspires rage in me. My funniest example though, and one I show my editing class, is an article bemoaning the incorrect use of words that then uses "disinterested" incorrectly. If you are going to write an article about it, and have it published in a writing magazine, you'd better get your language right. (And, yes, I realise I confused "marquee" and "marquis" the other day, but I was tired and hadn't proofread the posting because this is only a blog, and while I do like it to be all correct, I'm not as fussed as I would be about a published article. Does that just seem like me making excuses? Too bad.)
One that amuses me more than upsets me is the difference between "fortuitous" and "fortunate". "Fortuitous" means "accidental", but people use it all the time (especially in speech) when they mean "fortunate". Again, this is going to shift in meaning, if it hasn't done so already. It's a bit like mixing up "tortuous" and "torturous", though sometimes, for the car sick, a journey can be torturous because the road is tortuous.
"Alright" for "all right" drives me batty as an editor. As a teenager, I had a strong preference for the single word, but my Webster's lists it as "inferior usage", and I now can't stomach the single word, and while the Cambridge style guide recommends using it, the Penguin Working Word doesn't acknowledge it at all. I'll always go with the what-doesn't-upset-anyone approach if I can, so as a writer, editor and teacher, I still correct this to two words, though I note that many of my students resist this change. (But then a surprising number of them insist on spelling "lose" as "loose" too.)
"Decimate" -- I still prefer the original meaning of culling one in ten, and so this is the way I use it in my novel. "The Great Decimation" is exactly that, in the Roman sense of the word. Of course these days it is more often used in the sense of "devastated" or "destroyed".
Others that frequently get misused are "personable", and "nauseous" being used for "nauseated" -- again this is changing, but some of my writing friends feel strongly about this particular misuse as well. (Though can we classify it as a misuse once that change has happened, for whatever reason?)