• Fluid



    From Latin fluidus ("flowing, fluid"), from fluere ("to flow"), akin to Ancient Greek φλύειν (fluein, "to swell, overflow"). Several related terms in English from Latin (fluent, flux), and cognate from Proto-Indo-European (via Germanic) with flow.



    (countable and uncountable; plural fluids)
    1. (physics) Any substance which can flow with relative ease, tends to assume the shape of its container, and obeys Bernoulli's principle; a liquid, gas or plasma.
      • 2013-03, Frank Fish, George Lauder, Not Just Going with the Flow, An extreme version of vorticity is a vortex. The vortex is a spinning, cyclonic mass of fluid, which can be observed in the rotation of water going down a drain, as well as in smoke rings, tornados and hurricanes.

    Derived terms

    Full definition of fluid



    1. (not comparable) Of or relating to fluid.
    2. In a state of flux; subject to change.
      • 2013-08-03, Boundary problems, Economics is a messy discipline: too fluid to be a science, too rigorous to be an art. Perhaps it is fitting that economists’ most-used metric, gross domestic product (GDP), is a tangle too. GDP measures the total value of output in an economic territory. Its apparent simplicity explains why it is scrutinised down to tenths of a percentage point every month.
    3. Moving smoothly, or giving the impression of a liquid in motion.
    4. (of an asset) Convertible into cash.
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