altitude
noun
ADJ. great, high | low | cruising The plane took off and climbed to cruising altitude.
VERB + ALTITUDE cruise at, fly at, maintain The aircraft maintained an altitude of 28,000 feet.| reach, rise to The aviators reported the columns of smoke rising to an altitude of 2,000 feet.| gain | lose The plane suddenly started to lose altitude.
ALTITUDE + NOUN sickness
PREP. at an/the ~ No trees will grow at that altitude.