The rules of Scrabble (in the box) state:
You may play any words listed in a standard English dictionary except those only spelt with an initial capital letter, abbreviations, prefixes and suffixes and words requiring apostrophes and hyphens. Foreign words in a standard English dictionary are considered to have been absorbed into the English language and are allowed.
The rules allow you to use whatever dictionary you fancy. However for tournament play and to a lesser extent club play, an agreed authoratative word list is certainly desirable.
In Australia, since the Australian Scrabble Players Association began, there have been concerted efforts to make sure that an agreed list of words was available. In the early years, there was an agreed dictionary, the Chambers Dictionary, which was comprehensive and in tune with the needs of word game players. However judging words was difficult. Words were sometimes hard to find and it was not always clear what the inflections of words were. And arguments could arise about how a word might meet the allowability criteria. The first word list in the world which attempted to show all allowable words, including inflections was ASPAL, created in Australia. Updated and extended versions of such word lists were produced over the years, both here and overseas.
Much work goes into the preparation of a list of allowable words. The list has been updated every five years. Each word must conform to the criteria set out in the rules. Much scholarship goes into aspects such as verb forms, plurals etc. For most of this century, this work is done by editorial staff of a dictionary publisher (Collins) authorised by the trade mark holder (Mattel), working in close consultation with the Dictionary Committee of WESPA.
Collins Scrabble Words is the list used. The most recent editions are 2019 and 2022 (which deletes about 400 words, see censorship) details. In the 2019 edition, the Dictionary Committee of WESPA, principally Darryl Francis and David Sutton, explained the extent of the list thus:
Rules for the Scrabble word listOnly includes words of between 2 and 15 letters in length Does not include proper nouns, place names, and words with an initial capital letter, unless such words can also be spelt with a lowercase initial letter Does not include abbreviations, prefixes, suffixes, words requiring apostrophes or hyphens Includes foreign words that are considered to have been absorbed into the English language Includes inflected forms, such as plurals and verb forms, eg plumb, plumbs, plumbed, plumbing Includes words that are old, obsolete, dialectal, historical and/or literary Includes World English, including spelling and variants from the US, South Africa, Australia, New Zealand, etc Includes words that are denoted contractions, short forms and slang Includes words which may be deemed rude or offensive.
In April 2021 Mattel, the trademark holder in most of the world made an announcement that they would amend the rules of Scrabble to exclude so called hate words. Read more …
CSW 2022
2 to 15 letter words
Collins Scrabble Words. Available as a hardback. It has words up to 15 letters long, including inflected forms. There are more than 279,000 words. Compared with the 2019 list, it has 419 words deleted.
Collins Scrabble Dictionary 2022
A paperbackwith words between 2-8 letters in length giving short, succinct definitions (newly updated).
On Sale 7 Sep 2022
ISBN: 9780008523954
Pages 832
CSW 19
2 to 15 letter words
Collins Scrabble Words. Available as a paperback from booksellers. It has words up to 15 letters long, including inflected forms. There are more than 279,000 words
Collins Scrabble Dictionary
2 to 8 letter words
This is a rudimentary dictionary where the definitions are, as described by the publisher succinct and practical
. In many cases only a single definition is given. It labels a part of speech, but often the part of speech chosen for display is chosen not bound by common usage, but in order to validate inflections given elsewhere. Inflected forms are listed in true alphabetical sequence with a cross reference to the root word.
Other books have been produced which are aids to organised study.
Two and three letter words: You can probably get this as a one page list from your Scrabble Club or state Scrabble organisation.
2,3 & 4 letter word Hook Book by Alan Matthews. This lists the words by length, with front and end hooks shown against each word.
Puzzler's Word Guide 2019 by Don Hadley. This lists all words with extensions and anagrams, and differentiates words new to the 2019 lexicon.
Bob Jackman's books. There are several books prepared by Bob Jackman