Interestingly, there are also 121 different transformations [1] you can apply to each dictionary word, from adding various prefixes and suffixes, trimming letters, and some more complex ones [2].
If the plain-text dictionary linked earlier [3] is accurate, it'd appear that the dictionary contains a lot of redundant forms.
[1] https://tools.ietf.org/html/draft-alakuijala-brotli-11#page-... [2] https://tools.ietf.org/html/draft-alakuijala-brotli-11#appen... [3] https://gist.github.com/klauspost/2900d5ba6f9b65d69c8e