NWL vs CSW: Scrabble Dictionaries Explained

NWL and CSW are the two official word lists for competitive English-language Scrabble. NWL (the NASPA Word List) is used in the United States and Canada. CSW (Collins Scrabble Words) is used in the United Kingdom and in most international tournaments. CSW is the larger list: it contains almost every NWL word plus tens of thousands of British, Commonwealth, archaic and technical words.

The two lists at a glance

These counts come from the exact word lists that power the Unknot Words solvers, so you can reproduce them: set the word unscrambler to a length and compare the US and UK results.

How the lists differ

CSW is (almost) a superset of NWL

All but about 3,700 of NWL's words are also valid in CSW. The reverse is not true: CSW adds roughly 88,000 words that NWL does not accept. In practice, if a word is good in North America it is very likely good everywhere, but many words that are routine in international play will be challenged off the board in a US game.

Two- and three-letter words

The short words matter most because they let you play in tight spaces and build parallel plays. CSW has 20 extra two-letter words: CH, DI, EA, EE, FY, GU, IO, JA, KO, KY, NY, OB, OO, OU, ST, UG, UR, YU, ZE and ZO. Among the three-letter words, CSW adds useful plays such as QIN, CAZ, BEZ and DUX, each of which puts a high-value tile into a tiny space.

Spelling and vocabulary

CSW includes British spellings and regional vocabulary from across the English-speaking world: Scots, Australian, New Zealand, South African and Indian English words appear alongside older literary forms. NWL is centred on North American usage. Both lists add new words with each edition, so recent arrivals such as OK, EW, EMOJI and VAX are valid in both.

Offensive words

Both organisations have reviewed slurs in recent editions, and their policies differ, which accounts for a small number of words found only in NWL. If you teach or play with children, see the note on school-friendly dictionaries below.

Which dictionary should you use?

• Playing in the US or Canada, at a club, in a NASPA tournament or in most North American apps: use NWL (the “US” option in our solvers).
• Playing in the UK, Australia, New Zealand or internationally, or in WESPA-rated events: use CSW (the “UK” option).
• Casual games at home: agree on one list before you start. Many families use whichever dictionary matches their country, then settle disputes with a solver instead of an argument.
• Wordle and other five-letter puzzles: either list works, because the solver only uses it to rule words out. NWL gives a shorter, more familiar list of candidates.

What about the Official Scrabble Players Dictionary?

The Official Scrabble Players Dictionary (OSPD) is a printed dictionary for home and school play in North America. It is based on the same research as NWL but focuses on shorter words and leaves out offensive terms, which makes it popular in classrooms. It is not used for tournament adjudication, and it gives definitions, which the competition word lists do not.

Do Words with Friends and other apps use these lists?

Not exactly. Words with Friends and several other mobile games maintain their own word lists, which overlap heavily with NWL but add and remove words to suit their audience. A word our solver accepts will usually, but not always, be accepted in those games.

Studying with both lists

Players who switch between regions often learn the NWL list first and then study the “CSW-only” words separately, starting with the two- and three-letter additions above. A practical way to drill is to run the same rack through our word finder with each dictionary and note which plays appear only in CSW.

Whichever list you choose, the words themselves are only half the game. Read Scrabble strategy basics to learn how to turn a good vocabulary into higher scores.