Let's break down the phrase:
* Plagosus: This adjective means "whipping," "striking," or "punishing." It refers to Orbilius's use of physical discipline in his teaching.
* Orbilius: This is the name of the teacher.
* Pupillus: This is the surname of the teacher, which can be translated as "pupil," implying his own experience as a student under a harsh teacher.
Therefore, "Plagosus Orbilius" literally translates to "Whipping Orbilius" or "The Punishing Orbilius."
This phrase has become a proverbial term for a strict and brutal teacher who uses physical punishment.