Semantics

We tend to think everyone defines a word in the same way. Except that they don't. Maybe, being in a multinational family, I'm more aware of this. Every couple months we have an incident that ends abruptly with: "Honey, I don't think that I think that word means what you think it means." Definitions get exchanged, problem is solved. We're both native speakers of English, that's not the issue. Culturally, though, words that look and sound the same mean different things. ("Best", for example, to my husband, means favorite. He says: This is my best song. He doesn't mean he wrote or sang the song. He means it's his favorite song.)
My husband came home from work the other day and commented about a fight two of his coworkers had that culminated in one hitting the other. (Both male.) We'll call them A and B. A and B had been goofing off and annoying each other all evening. A unplugged B's monitor from his computer and took the cable. B said: Put it back. A said: Say please. B hit A. (Not joke-hit, knocked the guy sideways hit.) I suspect that when A said: Say please, B heard something very different. Maybe an abusive parent or spouse has said that to him, I don't know. But what he heard wasn't what A thought he said.
Here's a great example, if you've read Nate's blog, http://bloggerblaster.blogspot.com at all, you're probably aware that he defines "Yankee" as someone who fought on the side of the North during the Civil War (War between the States or whatever else you care to call it), and their assorted descendants, and that saying he hates them is probably too mild. I get very defensive about "Yankee"s. So I could go have a big fight with Nate, but it would make no sense to do so. You see, I define the term differently. To me, "Yankee" is someone who fought against the British in the Revolutionary War. Far as I can tell, Nate's got nothing against my definition of "Yankee". Same word, different meanings. Both are technically correct. Does it matter? Not in this instance. I just allow for that difference when I read his blog.
But if it's someone in your family, and there's some word that sets them off, or that seems to inevitably lead to misunderstandings, it might be worth asking: How do you define that word, anyway?