I don't think there is any real significance to the fact that the term "shaving" does not appear in the Shulchan Aruch. Shaving is mentioned by rishonim, and a simple comparison of the Rema in Shulchan Aruch to the Rema in Darchei Moshe will show that in the former he speaks of "haircutting" regarding the same halachos that he speaks of "shaving" in the former. In other words, it is lav davka (imprecise).