Ukemi, a Japanese word literally meaning “passive”, but in martial arts referring to actively falling down so as to soften or even mostly negate the blow (refer to Wikipedia), is an action one can take in an act of knockdown evasion.
Essentially, by hitting the prescribed command at the right time (see teching), usually right as one is about to hit the ground hard, one’s character will slap the ground or roll, and ultimately get to wakeup faster.
This is a particularly good thing to act upon in games where the opponent can hit you on the ground, since you can’t defend against it very easily.
However, there is the occasional case where you may fall victim to the variant of meaty attacks known as “ukemi hunting”.