Plain English Meaning
A system of small openings on the outside of the airplane that feed air pressure to three flight instruments. One opening faces forward and senses the pressure of air being pushed into it as the airplane flies; the other openings sit flush with the side of the airplane and sense the surrounding air pressure. Together, these readings let the instruments show how fast you're going, how high you are, and whether you're climbing or descending.
Full Definition
An aircraft system that supplies the air pressure information needed by the airspeed indicator, altimeter, and vertical speed indicator. It uses a pitot tube to capture ram (impact) air pressure from the aircraft's forward motion and one or more static ports to sense the still, ambient air pressure outside the aircraft. The instruments compare these two pressures to display airspeed, , and or .