altitude (n.) Look up altitude at Dictionary.com
late 14c., "elevation above the horizon" (of stars, planets), from Latin altitudinem (nominative altitudo) "height, altitude," from altus "high," literally "grown tall," from PIE root *al- (3) "to grow, nourish" (see old). General sense "space upward, height, vertical extent" is from early 15c. Related: Altitudinal; altitudinous.