Scrabble
There are special Scrabble dictionaries used for the game. In these dictionaries, all the allowed words (words that can be played during the game) are listed. When playing according to the proper rules, a player can not use a dictionary. However, if one player puts a word on the board, and another player says it is not an allowed word, then the players may check the dictionary. If the word is not in the dictionary, the player who played the word must take their letters back and lose their turn.