ENGLISH
REFERENCE

hydraulic

adj. · v.
US //haɪˈdɹɔɫɪk// UK //haɪdɹˈɔːlɪk// hy·draulic
  1. 1 operated by liquid pressure (adj.)
    B2 Upper Intermediate Technical Science

    describes a machine or tool that works by using liquid under pressure to move its parts.

    relating to or operated by the pressure of a liquid, such as oil or water, moving through a confined space.

    Example

    The mechanic had to fix the hydraulic brakes on the truck because they were leaking oil.

    Example

    The aircraft's hydraulic system failed during the descent, forcing the pilot to rely on the mechanical backup to lower the landing gear.

    Usage

    Usually placed before the noun it describes.
    • fluid powered
    • pressurised
  2. 2 related to water (adj.)
    C1 Advanced Technical Academic Science

    having to do with water or the way water moves.

    pertaining to water in motion or the study of water engineering.

    Example

    Engineers studied the hydraulic flow of the river to prevent flooding in the town.

    Example

    The city invested in a new hydraulic infrastructure to manage the seasonal overflow from the surrounding mountain streams.

    Usage

    Common in engineering and environmental science contexts.
  3. 3 to mine with water (v.)
    C2 Proficiency Technical Archaic

    to use high-pressure water to wash away earth and find minerals like gold.

    to conduct mining operations by using high-pressure jets of water to dislodge rock material or move sediment.

    Example

    During the gold rush, many miners began to hydraulic the hillsides, which caused a lot of damage to the land.

    Example

    Nineteenth-century companies would hydraulic entire mountainsides to extract gold, leading to significant environmental degradation and downstream siltation.

    Usage

    This transitive verb is primarily used in historical or specialised mining contexts.
    • sluice
Origin

From French hydraulique, from Latin hydraulicus, from Ancient Greek ὑδραυλικός (hudraulikós, “of a water organ”), from ὕδραυλις (húdraulis, “water organ”), from ὕδωρ (húdōr, “water”) + αὐλός (aulós, “pipe”).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Last updated June 20, 2026