from
The Collaborative International Dictionary of English v.0.48
G suit \G suit\ G-suit \G-suit\ n. [gravity + suit. 1944[MW10]]
(Aeronautics)
A suit worn by aviators and astronauts, designed to
counteract the effects of high accelerations experienced in
aerial maneuvers, in particular to avoid unconsciousness;
called also {anti-g suit}. It exerts force on the abdomen and
legs to prevent blackouts by counteracting the tendency of
blood to accumulate below the heart, thus reducing the supply
to the brain, when the forces due to acceleration are
directed from head to toe.
[PJC]