What is Olympus Mons?
Olympus Mons meaning in Planetary Science terminology / glossary / dictionary is:
Largest shield volcano on Mars. Located in the Tharsis region at 18.5oN, 133.2oW, it is 624 kilometers in diameter and rises 18 kilometers over its surroundings. The volcano is rimmed by a 6-kilometer-high scarp. The summit has nested circular depressions, calderas, formed by collapse after repeated withdrawal of magma and eruptions of lava. The last major summit volcanism on Olympus Mons ceased about 150-400 million years ago, based on crater counting.