A satrap was a governor of a province in the Achaemenid Persian Empire.
The word comes through Greek satrapēs from an Old Persian term commonly reconstructed as xšaçapāvā, meaning something like protector of the realm. Satraps administered large regions, collected tribute, maintained order, and often commanded troops. Their provinces were known as satrapies.
Persian kings used satraps because the empire covered a vast area containing many languages, religions, and local political traditions. Satraps generally worked with local elites rather than replacing every existing institution. The king also used royal inspectors and military officials to limit provincial independence.
Some satraps became powerful enough to rebel, especially during periods of succession crisis. The title continued after the Achaemenids under later Hellenistic and Iranian rulers, so “satrap” can describe provincial governors beyond the original Persian empire.