Here are the Google trends for REST APIs and REpresentational State Transfer:
https://trends.google.com/trends/explore?date=today%205-y&q=REST%20APIs
https://trends.google.com/trends/explore?date=today%205-y&q=%2Fm%2F03nsxd
These trends indicate that the interest in REST is growing over years, and very different definitions of REST from various sources is very confusing.
So, is it time for W3C to put out a spec for REST?