Drawing electoral district boundaries to advantage a party or group, typically by packing opponents' voters into a few districts or cracking them across many so they cannot win.
In more detail
The word dates from 1812, when Massachusetts Governor Elbridge Gerry approved congressional districts drawn to help his party and a Federalist newspaper likened one district to a salamander. It matters mainly under single-member districts. In Rucho v. Common Cause (2019) the US Supreme Court held that partisan gerrymandering claims are political questions beyond the reach of federal courts, pointing to state-level and congressional avenues for reform.