The deliberate tampering with the boundary of constituencies in order to win more seats is called

Gerrymandering is the deliberate manipulation or tampering with the boundaries of electoral constituencies, wards, or districts to benefit one political party or group over another. The purpose of gerrymandering is to achieve a disproportionate representation in the legislative body by manipulating the demographics of the electoral constituency. This can be done in several ways, such as dividing or combining existing constituencies, redrawing boundaries to include or exclude specific areas, and altering the size or shape of constituencies to influence the outcome of an election in favor of a particular political party or group.