I think it's probably fine. Especially if I am the 1st and only to ever ask. Admittedly, I am not the best at associating a meaning via context. I liked what you said; "Host = ISP because they are hosting my internet connection." Given that I was operating a web test on a web test site, the simplest explanation would be the one you intended. Though I will say, my second guessing arose from the possibility that TNM may have captured my domain and used it to test the connection speeds to the Host that Hosts my websites or the Host that Hosts my email, etc. However, reading further I now Know there are a fixed set of participating servers. (hosts)
"Server" is another one of those words.
As a sidebar I will tell you that the section on improving connection speed was good. I found a couple of not nice things on my Windows box after reading that.
And, as I read through the section on 1.1.1.1 DNS - I was forced to learn a lot more about DHCP than I ever wanted to know. I was hosting DHCP on my router for the LAN but all it was doing was using DHCP pass through from the ISP so I was still getting their DNS, and so forth and so on.
Anyway - great site. I love this test. I run it every morning.