The traditional distinction in society, amongst free men, was expressed as "eorl and ceorl" ('earl and churl') though the term 'Earl' took on a more restricted meaning after the Viking period. The noble rank is designated in early centuries as "gesiþas" ('companions') or "þegnas" ('thegns'), the latter coming to predominate. After the Norman Conquest the title 'thegn' was equated to the Norman 'baron'. A certain amount of social mobility is implied by regulations detailing the conditions under which a ceorl could become a thegn. Again these would have been subject to local variation, but one text refers to the possession of five hides of land (around 600 acres), a bell and a castle-gate, a seat and a special office in the king's hall. In the context of the control of boroughs, Frank Stenton notes that according to an 11th-century source, "a merchant who had carried out three voyages at his own charge also been regarded as of thegnly status." Loss of status could also occur, as with penal slavery, which could be imposed not only on the perpetrator of a crime but on his wife and family.