Originally from a conversation about dictionary service options with Justin in regards to the UIO+ work that we anticipate using for the SJRK platform as learner scaffolding, I'm pulling together some links from quick research I did.
This is not about the following scenarios:
This is about available online APIs for dictionary word definitions, and libraries that access them or make them easier to use.
Wiktionary supports the standard MediaWiki API - this basically lets you return page markup in a somewhat parseable format.
Many dictionary API services exist, including from the well-known dictionary publishers. These are examples, not comprehensive:
This needs filling out! Wiktionary has non-English versions available such as (https://fr.wiktionary.org/wiki/Wiktionnaire:Page_d%E2%80%99accueil), but their quality is not certain.
Some natural language libraries, like https://github.com/NaturalNode/natural, may have dictionary features.