The lumbar is the region of the spine between the diaphragm and the pelvis; it supports the most weight and is the most flexible. The adjustable lumbar mechanisms in seats allow the user to change the seat back shape in this region, to make it more comfortable. Some seats are long enough to support full thigh.
A bucket seat is a seat contoured to hold one person, distinct from bench seats which are flat platforms designed to seat multiple people. Bucket seats are standard in fast cars to keep riders in place when making sharp or quick turns.
