Frontier world was a term used to designate planets on the edge of a boundary.
Members of the Great Houses used "frontier world" to describe worlds on the frontier in time in the far future. These included Zo la Domini (PROSE: The Book of the War) and Frontios. (PROSE: Frontios)
Muriel Joy, a metamorph artefact dealer, often profited off despots and dictators from the frontier worlds by acquiring and selling them stormtroopers or first editions of Mein Kampf, which which they would establish and build their regimes. (AUDIO: A Blind Eye)
Part of the Daleks' Great War took place along the frontier in space between Earth space and Draconian space. (PROSE: The Evil of the Daleks, TV: Frontier in Space) One historical account held that the Combined Galactic Resistance had seen action in this region during the conflict. (PROSE: The Whoniverse) During humanity's 41st century conflict against the New Dalek Paradigm, Ogrons from these so-called frontier worlds were captured and taken to Station 7. (COMIC: The Only Good Dalek)