I've definitely heard it before, though "body font" seems to be much more prevalent. It's probably a literal translation from a continental Germanic language, e

I've definitely heard it before, though "body font" seems to be much more prevalent. It's probably a literal translation from a continental Germanic language, e.g. Dutch has "broodtekst" though the word refers to the actual body copy, not the font. German has "Bröttext".