A distinct type of kicking strike which is physically distinguishable by striking in a linear Line of Travel - making contact with the knife-edge of the foot.

Comments:

This kick does not necessarily refer to direction, but rather the point of contact of the foot (the side).

By definition, this kick either uses a Thrusting (or Snapping) Method of Execution.

From one perspective, this kick is the lower body equivalent to the hand-sword.

The word side, in this case, is equivalent to flank, but also equivalent to weapon contact point.

Typically, contact is made with the edge portion of the foot closer to the heel than the toes. This allows for the leg to back the kick and thus creating better overall Body Alignment.

A.K.A.:

Knife Edge (kick)

Derivation:

This kick derives its name from the fact that it is practiced as being delivered with the side of the foot - not to any specific direction (i.e. to the side).

Historically speaking, this kick was referred to as the Knife Edge kick. That name was eventually replaced (in the early 1970's) with side kick.