Which dictionary does Scrabble use? CSW24, NWL2023 and OSPD compared
There is no single Scrabble dictionary. Which word list applies depends on where you play and which game you are playing, and a word that is fine in one is challengeable in another. This page is the reference: who publishes each list, how big it is, and where the original lives.
Editions and sizes below were checked in August 2026. Word lists are revised every few years — if you are reading this much later, treat the edition names as a starting point and check the publisher.
The four lists this site checks
| List | Short name | Published by | Where it applies |
|---|---|---|---|
| Collins Scrabble Words | CSW, SOWPODS | HarperCollins | Tournament play in most of the world |
| NASPA Word List | NWL, TWL, OTCWL, OWL | NASPA | Tournament and club play in the USA, Canada, Thailand |
| Official Scrabble Players Dictionary | OSPD | Merriam-Webster | Home and school play in North America |
| Words with Friends | WWF | Zynga | The Zynga games — not Scrabble at all |
Each of those pages shows which edition we hold, how many words that is in our database, and when we last checked it. Those numbers stay there rather than here, so there is one place to look and it cannot quietly fall out of date.
Where each list actually comes from
Collins Scrabble Words — the big one
Published by HarperCollins and sanctioned by WESPA for international play. The current edition is CSW24, which became the official tournament lexicon at the start of 2025. Published breakdowns by word length add up to roughly 280,900 words of two to fifteen letters — the largest of the four by a wide margin.
CSW24 added 1,816 words to the previous edition and removed three, along with their inflected forms, as offensive. That is the pattern for Collins revisions: small additions, rare deletions, and the deletions are almost always about offensiveness rather than about a word ceasing to exist.
Where the original is: the printed Collins Official Scrabble Words, and the free single-word checker at scrabble.collinsdictionary.com. The list itself is HarperCollins copyright material and is not published as a downloadable file for anyone to reuse.
NASPA Word List — North American tournaments
Maintained by the North American Scrabble Players Association. The current edition is NWL2023, the sixth, in force for tournament play since early 2024. It runs to roughly 192,000 words of two to fifteen letters. NWL2023 introduced more than 4,500 words over NWL2020, drawing on the new edition of the OSPD and on long words from the Canadian Oxford Dictionary.
You will still see this list called TWL, OTCWL or OWL — those are older names for the same lineage, and most word finders (including the switch on our word finder) still label it TWL because that is what players search for.
Where the original is: NASPA, at scrabbleplayers.org. The book is a members-only publication sold through the NASPA store; NASPA also licenses the list to software developers, which makes it the one list of the four with a documented, legitimate route into an application.
Official Scrabble Players Dictionary — the book on the shelf
This is the consumer dictionary: a real book with real definitions, published by Merriam-Webster and endorsed by NASPA for recreational and school play. The current one is the seventh edition, copyright 2023, with more than 100,000 playable words.
The critical detail people miss: OSPD only covers words of two to eight letters. It is not a smaller tournament list, it is a differently scoped book. It also leaves out words judged offensive, which is exactly why it is the one you hand to a child and not the one used at a tournament.
Where the original is: the printed OSPD, seventh edition from Merriam-Webster, ISBN 978-0-87779-577-3 in paperback. There is no OSPD word-check API: Merriam-Webster's developer API covers its Collegiate and learner dictionaries, not this list.
Words with Friends — a different game entirely
Zynga's list is not a Scrabble list and never was. It grew out of ENABLE, a public-domain word list assembled in the 1990s, and has been edited ever since: thousands of additions, and removals of slurs and other words Zynga did not want in a mass-market game. Estimates put it at roughly 173,000 words.
That history explains the quirks players complain about. Vape is playable but its inflections may not be; bff and fomo are in while lol is out. There is no rule to learn here, because the list was not built from a rule.
Where the original is: nowhere public. There is no book and no official download; the only authoritative checker is the game itself, which simply refuses an invalid word instead of letting you play it and be challenged.
Why the four numbers do not line up
| List | Current edition | Approx. size | Word lengths |
|---|---|---|---|
| Collins | CSW24 | ~280,900 | 2–15 |
| NASPA | NWL2023 | ~192,000 | 2–15 |
| OSPD | 7th edition | 100,000+ | 2–8 only |
| Words with Friends | continuously edited | ~173,000 | 2–15 |
Comparing those totals directly is a mistake, and it is the mistake behind most arguments about which dictionary is “bigger”. OSPD stops at eight letters. Collins and NASPA both go to fifteen but disagree about tens of thousands of entries. Published comparisons of CSW24 against NWL2023 put roughly 88,000 words in Collins that the NASPA list does not have, and about 3,700 going the other way — of which only around 130 are short enough to appear in OSPD's range at all.
The clearest place to see the gap is the two-letter words, because you can hold the whole set in your head. Collins has 127 of them; the NASPA list has 107. The twenty that Collins accepts and North American tournaments do not:
CH, DI, EA, EE, FY, GU, IO, JA, KO, KY, NY, OB, OO, OU, ST, UG, UR, YU, ZE, ZO
Play one of those at a club in Boston and it comes off the board. Play it in London and it stands. Our two-letter word list marks which list accepts each one, and the finder respects whichever lists you have switched on.
Who owns the words
Two separate things get confused here, and the distinction matters if you ever plan to build something with a word list.
- The lists are copyrighted data. CSW belongs to HarperCollins, NWL to NASPA, OSPD to Merriam-Webster. None of them are public domain, and none can be redistributed freely. ENABLE, the ancestor of the Words with Friends list, is the exception: it was released into the public domain.
- The name is a trademark, and a different owner's. SCRABBLE is a registered trademark of Hasbro in the United States and Canada, and of Mattel everywhere else. Collins uses the name on its word lists under licence from Mattel. A licence to use a word list is not a licence to use the name.
This is why word finders differ from each other and why none of them show you the publisher's own file. It is also why we say plainly, on each dictionary page, which edition we hold and when we last checked it — a list without a date is a claim without evidence.
Which list should you be using?
- Club or tournament in the USA, Canada or Thailand — the NASPA list. Nothing else counts, and Collins-only words will be challenged off.
- Tournament anywhere else, or an online game following WESPA rules — Collins.
- Family game at home in North America — OSPD, which is what the book in the box points at.
- Words with Friends — the WWF list only. Use the Words with Friends cheat, not the Scrabble finder: the tiles and the scores are different too.
Common questions
Is SOWPODS the same as Collins? Effectively yes. SOWPODS was the old name for the merged British and American lists; the modern maintained version is Collins Scrabble Words, and most software still offers “SOWPODS” as a synonym.
Why does my app accept a word this site rejects? Different list, or an older edition of the same list. Both are common: apps update their lexicon on their own schedule, and some never do.
Do the lists have definitions? OSPD does — it is a dictionary in the ordinary sense. The tournament lists are lists: NASPA publishes definitions alongside NWL, while the Collins tournament list is primarily a validity list. That is why a word can be perfectly legal and mean nothing to you.
Where can I check one word officially? Collins has a free checker on its site, Words with Friends has one built into the game, and for the North American lists the authority is the book or a NASPA-licensed tool. Our dictionary answers for all four at once, which is faster, and each answer says which list it came from.
Lists change, and word finders rarely say so
New editions add words and remove them. A word learned five years ago may no longer be playable — see words removed from OTCWL2018 for what that looks like from the player's side.
Most word finders show you a list without saying which edition it came from or when it was last updated, which means you cannot tell whether their answer matches the game in front of you. Every one of our dictionary pages carries that information, including when it is missing.