There was good money in the word business. Then came the internet and, with it, ready-to-hand answers to all questions lexical. If you are writing on a computer, it’s almost impossible to misspell a word anymore. It’s hard even to misplace a comma, although students do manage it. And, if you run across an unfamiliar word, you can type it into your browser and get a list of websites with information about it, often way more than you want or need. Like the rest of the analog world, legacy dictionaries have had to adapt or perish. Stefan Fatsis’s “Unabridged: The Thrill of (and Threat to) the Modern Dictionary” (Atlantic Monthly Press) is a good-natured and sympathetic account of what seems to be a losing struggle.