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.