Since Scrabble adopted an official lexicon in 1978, one thing has been constant: People have never stopped arguing about what is or isn't a word. Players have defended the game by noting that its letter strings--from AA (a kind of Hawaiian lava) to ZZZ (an interjection for sleep)--could be found in a bunch of standard North American dictionaries, books that have been used through the years to compile and revise Scrabble's tournament word list. But after an update last month introduced dozens of suspect words, riling up the community of competitive players, that's becoming harder to do. The linguistic tumult began in September, when the organization that maintains the word list used in club and tournament Scrabble, NASPA Games, published a draft of its update. The NASPA list includes all of the words in the Official Scrabble Players Dictionary, the go-to source for living-room and app players in North America, plus a lot more.

In recent weeks, a web-based word puzzle called Wordle has become a popular daily distraction. Suddenly, millions of people are focused on their vocabulary of five-letter words, and are newly aware of concepts like letter frequency and letter position as they strategize about the best opening words and faster solutions. For these people, Wordle is captivating. Previous research can help us understand how our brains respond to word games, and why we love them. Wordle is a single-player puzzle that combines elements of several games, including Scrabble and Battleship.