What are “extraordinary” and “ordinary” waves?

When a linearly polarized radio wave enters the ionosphere, the Earth's magnetic field splits it into two separate components known as the 'ordinary' (O-wave) and 'extraordinary' (X-wave) waves. These waves become elliptically polarized and propagate independently through the ionized plasma. They travel at slightly different speeds and are refracted differently by the ionosphere, which often leads to different critical frequencies for each wave. Distractors focusing on 'rare long-skip propagation' or 'long/short paths' simply borrow the everyday meanings of the words rather than their scientific definitions within magneto-ionic theory.