altimeter

from WordNet (r) 3.0 (2006)

altimeter
    n 1: an instrument that measures the height above ground; used
         in navigation

from The Collaborative International Dictionary of English v.0.48

Altimeter \Al*tim"e*ter\, n. [LL. altimeter; altus high +
   metrum, Gr. ?, measure: cf. F. altim[`e]tre.]
   An instrument for taking altitudes, as a quadrant, sextant,
   etc. --Knight.
   [1913 Webster]