You Could Look It Up
Q. I am trying to find the definition of “roman style” as contrasted with “Times New Roman.”
A. “Roman style” means regular (not italic) type. It can be in any typeface (or “font”). Times New Roman is the name of a typeface, which can appear in roman, italic, bold, and other styles. In CMOS you can find a definition of roman type in the glossary (appendix B).