Thank you for your question! Unfortunately, this API endpoint has never really been extremely useful. We hope to be upgrading it soon, and would love feedback.
It sounds as if you are looking for a measure of a word's "lexicality" -- how acceptable it is as a word. We don't (yet) have a single endpoint or call you can make to determine this, since people's use cases differ widely.
We are hoping to update the Wordnik API to include a "wordishness" or "lexicality" endpoint that would give a confidence score of wordishness (e.g. 'cat' = 100% confidence; 'megacattishnessosity' .... MUCH lower confidence :) ). If you'd like to be kept in the loop on new developments in the API, you can join our announcements list here: http://eepurl.com/bPCg0D
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