"Frei materialist" is the best I can come up with. I have a deep sense that everything meaningful about the world is an ephemeral program running on the engine we call "physics". A different arrangement of material and the world would be completely different but ultimately indistinguishable from an atomic or relativistic perspective. Therefore all of the meaning and human-scale things in the world are up to us (and our genetics, and our history, and our culture) to sort out amongst ourselves, and the universe at large has nothing to do with it. The universe doesn't only not give a shit, it is incapable of giving a shit. And therefore we are free.
Orthodox Jews divide the world up into the frum and the frei. Frum means "pious" and refers to the Jews who follow or strive to follow the mitzvot, or 613 commandments (have kids, keep shabbos, don't mix wool and linen, etc). It's the word that the Orthodox use to describe themselves. Frei means "free," as in, not constrained by the mitzvot, free to have kids or not, keep shabbos or not, and so on. My sense of the universe as basically indifferent to us aligns fairly well with that idea.