I think we’re gonna have to agree to disagree on definitions. To me, and I believe, to most people, an SPA refers to a UI/UX design pattern that can be implemented with any number of underlying techniques. I would also say that the Wikipedia page for SPAs (on the assumption that wikipedia is a valid tool for establishing consensus for definitions) supports my definition:

A single-page application (SPA) is a web application or website that interacts with the user by dynamically rewriting the current web page with new data from the web server, instead of the default method of a web browser loading entire new pages.

There are various techniques available that enable the browser to retain a single page even when the application requires server communication.

And it goes on to list frameworks, AJAX, Websockets, etc.