hydraulic (adj.)

"pertaining to fluids in motion," c. 1600, from French hydraulique, from Latin hydraulicus, from Greek hydraulikos (organon) "water organ," the name of a musical instrument invented by the Egyptian Ctesibius, from hydr-, stem of hydor "water" (from suffixed form of PIE root *wed- (1) "water; wet") + aulos "musical instrument, hollow tube, pipe" (see alveolus). Extended by the Romans to other water engines.