The term is derived from the Greek word akron/akra, meaning border; similar border guards, the limitanei, were employed in the late Roman and early Byzantine armies to guard the frontiers (limes). In official Byzantine use, the term is non-technical, and used in a descriptive manner, being generally applied to the defenders as well as the inhabitants of the eastern frontier zone, including their Muslim counterparts. The popular image of the Akritoi has been heavily influenced by their portrayal in the Acritic songs, and refers to the military troops stationed along the Empire's border. In reality, the Byzantine troops stationed along the edges of the Empire were a mixture of professional troops and local thematic militia, as well as irregular units that constituted the Akritai or Apelatai