hydraulic (adj.)youdaoicibaDictYouDict[hydraulic 词源字典]
c. 1600, from Greek hydraulikos organon "water organ," from hydr-, stem of hydor "water" (see water (n.1)) + aulos "musical instrument, hollow tube" (see alveolus). Extended by the Romans to other kinds of water engines.[hydraulic etymology, hydraulic origin, 英语词源]