Giant Planet Orbiting a Brown Dwarf Spotted, Re-Opening Debate Over What Makes a Planet

When something is too big to be called a planet and just massive enough to become a star, where do scientists draw the 'planet'/'not a planet' dividing line?

from gizmodo http://www.gizmodo.co.uk/2018/03/giant-planet-orbiting-a-brown-dwarf-spotted-re-opening-debate-over-what-makes-a-planet/