1. [usu. treated as sing.]
the branch of science and technology concerned with the conveyance of liquids through pipes and channels, esp. as a source of mechanical force or control.
hydraulic systems, mechanisms, or forces.
Physical science and technology of the behaviour of fluids
in both static and dynamic states. In 1795, Joseph Bramah
invented the hydraulic press. In the 19th century, hydraulic power was used for cranes and swing-bridges. Oil later replaced water as the main working fluid. Most modern cars have hydraulic brakes. See also fluid mechanics