For the entire time I borrowed this book, I thought the title was "Posh", which was weird, but then again, it is one of the entries. And then I tried to search for the book on Goodreads....
Port Out, Starboard Home is a mini-encyclopedia about various English words and phrases (the fancy term for this is called etymology). It's arranged in alphabetical order, and there are cross-references for related words. In each entry, the author talks about the different folk etymologies there are and which is the true origin (if there's any).
I found this book to be really interesting. I haven't heard of most of these folk etymologies, so they were all new to me. I haven't really considered the origins of words before, and as I read, I was thinking, we should have a competition to see who can make up the most plausible story for a certain word (that we can draw at random) and see who can come closest to the truth. [Disclaimer: I was inspired by the book No More Naughty, where to learn the meaning of words, the children were asked to make up their own definitions first and vote for the most plausible sounding one.]
If you're wondering about the origins of some of your favourite words (or at least, some theories about the origins of the word), you should give this book a go. It's a light-hearted and readable book. And since it's educational, that's got to have some bonus points.