Merriam-Webster, publisher of several dictionaries and thesauruses, has launched a Developer Center and is making available an API that is free for non-commercial use.
According to the announcement:
The Merriam-Webster Dictionary API gives developers access to a comprehensive resource of dictionary and thesaurus content as well as specialized medical, Spanish, ESL, and student-friendly vocabulary. Make your applications better by integrating our authoritative definitions, etymologies, audio pronunciations, synonyms and antonyms, and more. Our robust API empowers developers to enhance word games and create educational, language learning, and other word-related applications for the digital environment.
On registration, developers can request two API Keys from this list:
If you want more than two keys, and also if you want to use the API in an app that makes money (from sales or from in-app purchasing or advertising) you will have to contact Merriam-Webster.
Given the popularity of word games, and their obvious educational applicability, this API opens up lots of possibilities.