Definition of "altimeter" []

• An instrument for determining elevation, especially an aneroid barometer used in aircraft that senses pressure changes accompanying changes in altitude. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "An altimeter measures the distance from the satellite, where the altimeter is placed, to the surface of the Earth."
• "The Service Release limits operations involved in these activities to: no prolonged flights over water; no flights with sand filters fitted; no night flights using night vision devices; no flights where the radar altimeter is to be relied upon, and; no take-off, landing or operations close to the ground above 5000 foot pressure altitude."
• "A standard altimeter could not tell the astronauts when they reached their perilune because an altimeter was an instrument that determined altitude based on changes in atmospheric pressure and the Moon has no atmosphere."