I am a non-stop reader. I always have at least one, usually two books going at once. At the moment I'm reading a very well researched bio of Anne Boleyn. (The Lady in the Tower by Alison Weir) plus I just received the copy of White Mischief by James Fox that was recommended to me by a loyal reader (thanks Kittie!).
In turning to the pages of White Mischief I found something I'd seen before, but never understood. The mention of (and I'm making this name up) Lord Hobnobble of that Ilk. Of that ilk? What the huh? I've seen this before and finally got around to looking it up. It refers to cases where a person's surname and the title of his estates are the same. In this case, it would be Lord Hobnobble of Hobnobble. So instead of, say, Lord Harfsniffle of Fleem, we have Lord Hobnobble of that Ilk. I want an ilk!
The next surprise came from The Maltese Falcoln. There's a character in the movie played by Elisha Cook that Sam Spade refers to as "a gunsel." And from its use hard boiled detective fiction, I assumed it meant some kid who carries a gun. Turns out that Dashiell Hammet used the word intentionally, assuming that editors (or censors) would take it to mean the same as I. Imagine my surprise when I looked up the word and found a definition that was completely different. According to Wikipedia a gunsel is "a young man kept for sexual purposes." This makes perfect sense in terms of the plot of the book and the movie. An older man who has a younger protege. But it came as a total shock to find out that this word I always thought was something out of crime noir fiction was specifically used to mislead people into thinking it meant one thing when it really means something completely different.
And finally, this obscure and vaguely horrible eye-opener. A term I'd seen in many history books is a household title, the Groom of the Stool. It was apparently a position of some trust and respect in the king's household. And, finally looking it up, I discover ... ewww ... the Groom "presided over the office of royal excrement." Ohhh...you actually mean "stool." Ugh.