coplanar

/kษ™สŠหˆpleษชnษ™(ษน)/
adjective
  1. 1

    (of at least two things, usually lines or plane figures) Within the same plane.

  2. 2

    (of multiple planets or other orbiting bodies) Orbiting a central celestial object within the same orbital plane.

Source: https://en.wiktionary.org/wiki/coplanar