[consilient]

> Calling it “matter” is already making a huge set of assumptions.

Not really. "Matter" is not really a formal term of art, but in practice it usually means "not an elementary boson", or at the strictest "fermionic".

[AnimalMuppet]

Are there any massive elementary bosons that we currently know of?

[magicalhippo]

The W and Z bosons[1] have mass, a fair bit of it actually.

[1]: https://en.wikipedia.org/wiki/W_and_Z_bosons