You're mistaken then. Monolith is just project organization. Think microservices and then realize the monolith is on the other end of the spectrum. It's in the name.
You keep posting this. A monolith is a software architecture. It says nothing about there being one instance of that monolithic process or a billion any more than "microservice architecture" becomes untrue unless you have k instances of any particular service.
It's like saying "this thing says it is built as a suspension bridge, but there are ten of them, so I wouldn't call it a bridge."
If your definition of a monolith refers to a singular server, then I've never worked on a monolith in my life. Even the crufty old ASP apps I used to work on weren't monoliths.
This would also mean that deploying a microservice architecture onto a single server, using docker for example, would be considered a monolith. Or even better, any application that leverages a database on a separate server is no longer a monolith! That's way easier than rearchitecting your whole app.
I've never come across a definition for monolith in the context of software that had anything to do with the actual infrastructure employed
Nevertheless, that's a pretty common term when the compute portion of the application is a single tier, but that doesn't mean that the tier can't scale over many stateless compute nodes.