Words are checked against the ENABLE word list, which is in the public domain, with a short list of modern words added and a short list of offensive terms removed. With thanks to ENABLE’s originators, including Alan Beale and M. Cooper.
Some newer words come from the neol2016 neologism list in Alan Beale’s 12dicts package (wordlist.aspell.net), released by its author to the public domain. Thank you, Alan Beale.
three.js — MIT licence (licence text).