I understand your reluctance for using term "document". I don't like it much either when it comes to JSON entities, but I can't find any better term, much less a widely used one.

Look at the matter this way: CouchDB, MongoDB, and ElasticSearch, all use the term "document" to describe hash containing data of JSON-compatible model. They already do so, and they are quite well known in the field. It only makes sense to follow their lead, so your potential users can recognize capabilities of your application easier.