From mesos (middle) and toichos (wall). A dividing wall, a partition that separates. Used only once in the NT, in Ephesians 2:14, where it describes the barrier between Jews and Gentiles that Christ destroyed.
Paul declares that Christ 'has destroyed the barrier, the dividing wall of hostility' between Jew and Gentile (Ephesians 2:14). This likely alludes to the physical wall in the Jerusalem temple that separated the Court of the Gentiles from the inner courts — a wall that bore inscriptions warning Gentiles of death if they crossed. Christ's cross obliterated this division, creating one new humanity from the two. This is the gospel's radical social implication: in Christ, all walls of ethnic, social, and religious hostility are demolished.