Undergrip: A term referring to the type of drip which gymnasts use on uneven bars or high bar.  Hanging on a bar with your fingers facing you.  Also called a reverse grip.

Underswing: A release move from the high bar to the low bar. It starts on the on high bar facing low bar. The gymnast swings up and over the low bar with a half turn to a catch of the low bar. Also called a Shoot Over or Overshoot.

Uneven Bars: A women’s gymnastics apparatus consisting of two fiberglass composite bars - a low bar 148 centimeters high and a high bar 228 centimeters high and set a maximum of 150 centimeters apart. 

Uneven Bars: A women's event performed on the uneven bar apparatus, featuring circling skills, pirouettes, releases and re-catches and moves from one bar to the other. 
 

Gymnastics Dictionary