The Official Scrabble Players Dictionary (OSPD) is a dictionary developed for use in the game Scrabble, by speakers of American and Canadian English. Its publication began in 1978, through the efforts of the National Scrabble Association (NSA) Dictionary Committee and Merriam-Webster. It was the official source for tournament play until the 3rd edition removed some controversial words; since then, the "NASPA Word List" (NWL) (previously called the "Official Tournament and Club Word List"), which is based on the OSPD but with those words re-added, is used for tournaments in the USA, Canada, and Thailand. (The North American Scrabble Players Association took over from the NSA in 2009.)
Outside of the US/Canada/Thailand, other English-language Scrabble players used Chambers Official Scrabble Words (OSW) from 1988 to 2007. Mattel switched the international Scrabble dictionary publisher contract from Chambers to Collins in 2005; the Collins Official Scrabble Words or Collins Scrabble Words (CSW) and related Collins titles have been used since their first publication in 2007.
There was also a much less comprehensive "Scrabble Word Guide" by Edmund Jacobson and Jacob S. Orleans, published from 1953 through the early 1980s, that was commonly used until the OSPD and OSW/CSW.