Hydraulic means worked by the pressure of a liquid. Hydraulic brakes, a hydraulic ram, hydraulic fluid.
It works because liquid does not compress, so pressure applied at one end appears undiminished at the other, and a small piston can drive a large one with great force. Air compresses, which is why brakes use liquid and not air.
1adjectivehydraulicWorked by the pressure of a liquid.
“The mechanic raised the car on a hydraulic lift to look underneath.”
hydraulic is a quality.
Greek hydraulikos means of a water organ — hydor, water, plus aulos, a pipe.
Proto-Indo-European
*wed-
French
hydraulique
English, today
hydraulic
Built from
Borrowed from French hydraulique. From French hydraulique, from Latin hydraulicus, from Ancient Greek ὑδραυλικός (“of a water organ”), from ὕδραυλις (“water organ”), from ὕδωρ + αὐλός.
Etymology from Wiktionary, CC BY-SA