Personally, I prefer to talk about hosts, as this is a well-known concept. The fact that there is some ambiguity because hosts can be clustered and virtualized also isn't a huge surprise to most people, and can be spelled out for good measure.
"virtualize" means "as if it is real.
"virtualized host" means "muptiple entities behaving as if it is a single host".
So, for the purpose of network protocol, treat it as a plain host.
All the rest is internal implementation details within a host.
There is no room of confusion.