ngrm requires a list of words, separated by new lines,
to work from.
You can download big word lists from here:
You will need to remove the top few header lines from these files:
$ tail -n +3 twl06.txt > na-wordlist.txt
$ tail -n +7 sowpods.txt > eu-wordlist.txt
Because I couldn't find out what licenses these word lists are released under, they aren't included in the repository.