A set with the key names being the environment variable you’d like to set and the values being a list of paths to text documents containing lists of words. The various files will be merged, sorted, duplicates removed, and extraneous spacing removed. If you have a handful of words that you want to add to an already existing wordlist, you may find builtins.toFile useful for this task.

{
  WORDLIST = [ "${pkgs.scowl}/share/dict/words.txt" ];
}

{
  WORDLIST = [ "${pkgs.scowl}/share/dict/words.txt" ];
  AUGMENTED_WORDLIST = [
    "${pkgs.scowl}/share/dict/words.txt"
    "${pkgs.scowl}/share/dict/words.variants.txt"
    (builtins.toFile "extra-words" ''
      desynchonization
      oobleck'')
  ];
}