Perhaps corresponding to "serjo" and "sera" / "muthsera" of the Dunmer ?
Didn't the jerk face Earl of Clavius Vile say that cerum meant unwelcomed or something? Maybe I'm confusing it for something else.
I don't believe the "Sir" and Ma'am" translations are correct, as NPC's will call a single person both ceruval and cerum in the same discussion (i.e. Tarnavir, the former Chief Inquisitor uses both in addressing the questor during his initial conversation).