The Collaborative International Dictionary of English v.0.48:

Space suit \Space suit\, n.
   a protective suit covering the whole body, completely
   airtight and designed to withstand internal pressure, worn by
   astronauts to protect them from the vacuum and other hazards
   of outer space. It typically contains an air supply and other
   life-support equipment to allow functioning independent of
   any other equipment for a period of time while in space.
   [PJC]