Im not sure I don't define Usenet specifically. It wasn't the program (I've no memory of what it was, News or something like that.) The protocol is NNTP. Usenet wasn't a term we used a lot but when we did it kinda referred to the whole News eco system. So encompassing the software, protocol, forums and so on.

Kinda like we'd use yhe term "web" today to encompass HTTPS, browsers, servers and so on.