(I read the NYT article, but not watched the videos.)
I am not a lawyer, and I am not versed in US IP law. Their ToS (
https://www.wordnik.com/terms ) look confusing to me --- there are contradictory passages and it is not clear to me what license applies to the contents (if any at all).
Clearly, if you can retrieve/scrape (again, is this allowed by their ToS?) their contents, just save them as a CSV or XML file, then you can use Penelope to convert this file to the Kobo format.