For-Profit Dictionary/Synonyms/Antonyms Dataset

Question

So, I'm going to be making an application, but for one of the features to work, I'll need to be able to look up Definitions, Antonyms, and Synonyms for words.

The kicker here is that I'll need one that can be used for-profit, as I plan to make money from the application.

Any idea where I can find a dataset that matches my needs?

Answer 1

WordNet may be close to what you are looking for, and it can be used commercially.

http://wordnet.princeton.edu/

and the wiki article:

http://en.wikipedia.org/wiki/WordNet

Answer 2

You can use WordsAPI and buy its data set. According to the description on their website:

Purchase of the Words API data set entitles you to use the data as much as you want, for as long as you want...The only things you cannot do with the data are resell it, or use it in a service that competes directly with WordsAPI.

Also, you can download sample data (10% of the data set) for free.