The sebri was the lower-half social class, commoners, of the medieval Serbian state. The status of the groups comprising the class was regulated in medieval code of laws, such as Dušan's Code (1349). It included several groups, mainly divided into:
- The meropsi or merophe , dependent farmers. Other terms included zemljanin ("earthen [man]", from zemlja, "land"), Srbljin (from the Serb ethnonym), or zemljani ljudi ("earthen folk"). They served either the ruler, the church, or nobility. Medieval sources allows for understanding the legal position of the church's meropsi, while that of the ruler's and nobility's meropsi is deemed insufficient. The fact that there were three groups implies that their status was not identical, however, it has been established that their status did essentially not differ.
- The vlasi or pastiri , dependent shepherds. The multitude and likely prevalence of Vlachs (Romanized remnants; see Vlachs in medieval Serbia) among the shepherds made the term "Vlachs" a synonym for shepherds, similarly as the term Srbljin was sporadically used for farmers. The status of the vlasi was basically equal to the meropsi.
- The otroci , a type of medieval slaves. This group was closest to having complete deprivation of rights, similar to slaves (robovi), although this has for long and persistently been disputed in scholarship. The lord could free his otroci from that status, which points to similarity with slave status.
- The dependent (or rural) craftsmen and sokalnici . The craftsmen and sokalnici had a special status, which is unclarified from available sources.
- Partially also the rural clergy.