[banana_giraffe]

The source they used (freeDictionary) does all of the work of parsing wiktionary and giving you simple json object for each word. (It actually started life as a way to get the definitions out of Google's "define:" operator, but it seems those days are over)

It also, turns requests for some words, like "rolling" into definitions for their root word like "roll", even when wiktionary has distinct and useful definitions for the word, which makes it less than ideal for me.

[herewulf]

Turning "rolling" into "roll" is something a stemmer does. I'd imagine there are a number of JavaScript libraries readily available for this.