Crumple

Crumple, also known as Crumple Stun, is a gameplay mechanic first introduced in Street Fighter IV.

When hit into a crumple state, the opponent falls down to his knees before falling down onto the floor. A crumple is similar to stun in that it leaves the opponent vulnerable to attack, but its properties varies greatly. First off, only a grounded opponent can be crumpled. Secondly, from the moment the opponent is hit until they land on their knees, they will be treated as a grounded opponent, so any attacks will not juggle them. In addition, the crumpled opponent can be thrown during this time. Once their knees have touched the ground until they fall on their stomach, the opponent is treated as airborne opponent, and thus can no longer be thrown, but all attacks will pop them up into the air on hit.

The primary method of inflicting crumple stun on an opponent is through the use of a Focus Attack, though certain specials and supers can also inflict crumple stun. In Street Fighter X Tekken, many character's normals can inflict crumple stun, but only on counterhit.