Backfist Side Strike
The Backfist Side Strike strike is somewhat like a Rear Backfist Strike except that it's made to the side. In other words, the backfist is brought upward from waist-level in a vertical arc to strike an opponent to the side of your body.
This strike should not be confused with the Outward Backfist Strike which is also made to the side of the body, but in a horizontal motion - in front of the body - rather than a vertical motion.
By comparison, an Outward Backfist Strike is a strike that's made by bringing the backfist outward in a horizontal arc, starting from the opposite shoulder.