Words With Friends Instant Games combine the use of British and American dictionaries as source of words and definitions. There are more than 173,000 acceptable English words for use in the game.

For other languages, these are the dictionaries used:

Words With Friends Instant Games uses the Oxford Spanish word lists. It includes Castellano as well as other varieties of American Spanish.

All words labeled as a part of speech (including those listed of foreign origin, and as archaic, obsolete, colloquial, slang, etc.) are permitted with the exception of the following: proper nouns (words always capitalized), abbreviations, prefixes and suffixes standing alone or words requiring a hyphen or an apostrophe.

All diacritics are ignored but Ñ is accepted. K and W are absent and they cannot be used as blank tiles. There are no tiles containing LL, RR or CH letters. Two single letters will be used to represent them.

Words With Friends Instant Games uses the Oxford Italian word lists.

All words labeled as a part of speech (including those listed of foreign origin, and as archaic, obsolete, colloquial, slang, etc.) are permitted with the exception of the following: proper nouns (words always capitalized), abbreviations, prefixes and suffixes standing alone or words requiring a hyphen or an apostrophe.

All diacritics are ignored. The letters J, K, W, X and Y are absent and cannot be used in­game, or replaced by a blank tile.

Words With Friends Instant Games uses the Oxford Brazilian Portuguese word lists.

All words labeled as a part of speech (including those listed of foreign origin, and as archaic, obsolete, colloquial, slang, etc.) are permitted with the exception of the following: proper nouns (words always capitalized), abbreviations, prefixes and suffixes standing alone or words requiring a hyphen or an apostrophe.

While Ç is a separate tile, other diacritical marks are ignored. K, W and Y are absent and can not be used to replace blank tiles.

Words With Friends Instant Games use Oxford German word lists.

All words labeled as a part of speech (including those listed of foreign origin, and as archaic, obsolete, colloquial, slang, etc.) are permitted with the exception of the following: proper nouns (words always capitalized), abbreviations, prefixes and suffixes standing alone or words requiring a hyphen or an apostrophe.

All diacritics, except umlauts (Ä, Ö and Ü), are ignored. Umlauts (Ä, Ö and Ü) are accepted and can not be substituted for correspondent ligatures (AE, OE or UE). Eszett (ß) is not accepted and is replaced by SS using 2 tiles.

Words With Friends Instant Games use Oxford French word lists.

All words labeled as a part of speech (including those listed of foreign origin, and as archaic, obsolete, colloquial, slang, etc.) are permitted with the exception of the following: proper nouns (words always capitalized), abbreviations, prefixes and suffixes standing alone or words requiring a hyphen or an apostrophe.

All diacritics are ignored. Ligatures are represented with two letters: Œ becomes OE, and Æ becomes AE.