Players may agree on one or more dictionaries prior to the start of the game. Capitalized words, strictly foreign words, and abbreviations are not allowed.

A challenged player must always spell all new words formed completely including all letters represented by asterisk tiles. Two explanations may be required for an asterisk used in two directions to form two new words.

If the spelling offered by the player for any of the new words formed is not in any of the dictionaries agreed upon (applying their conventions for regular endings), a challenge made against the word is deemed to be successful. It does not matter if the word was found at some other time in some other dictionary. It also does not matter if the same tile play could have corresponded to the correct spelling. What you spell is what you played, except as noted below.

If a player provides a spelling that does not correspond to the tiles he/she played (this can happen), that, too, is deemed to be a successful challenge.

Having some idea of the breadth of the Dictionary you are playing with—Encyclopedic versus Collegiate—is another factor that makes a game of WildWords interesting.

When playing online, M/W's dictionary is a good source (link in Other Menu). Although this dictionary is limited, remember, it is limited for both players. It introduces a certain risk in playing an esoteric word. Also, the dictionary does not include some very reasonable "un" words if the definition is simply the opposite of the normal word.