from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A continuous, amorphous substance whose molecules move freely past one another and that has the tendency to assume the shape of its container; a liquid or gas.
  • adj. Of, relating to, or characteristic of a fluid.
  • adj. Readily reshaped; pliable.
  • adj. Smooth and flowing; graceful: the fluid motion of a cat.
  • adj. Changing or tending to change; variable: a fluid situation fraught with uncertainty.
  • adj. Characterized by or allowing social mobility: a fluid society.
  • adj. Convertible into cash: fluid assets.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. 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
  • adj. Of, or relating to fluid.
  • adj. In a state of flux; subject to change.
  • adj. Moving smoothly, or giving the impression of a liquid in motion.
  • adj. Convertible into cash.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Having particles which easily move and change their relative position without a separation of the mass, and which easily yield to pressure; capable of flowing; liquid or gaseous.
  • n. A fluid substance; a body whose particles move easily among themselves.

from The Century Dictionary and Cyclopedia

  • Capable of flowing; liquid or gaseous; consisting of a substance incapable of resisting forces (tangential stresses) tending to change its shape.
  • Not fixed or rigid; flowing; shifting; fluent.
  • n. A substance which flows or is capable of flowing; a substance which is incapable of resisting forces (tangential stresses) tending to change its shape without altering its size.
  • n. Some hypothetical supersensible substance conceived as analogous to known fluids. See fluidism.
  • n. See the adjectives.
  • n. See the adjectives.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. in cash or easily convertible to cash
  • n. a substance that is fluid at room temperature and pressure
  • n. continuous amorphous matter that tends to flow and to conform to the outline of its container: a liquid or a gas
  • adj. subject to change; variable
  • adj. affording change (especially in social status)
  • adj. characteristic of a fluid; capable of flowing and easily changing shape
  • adj. smooth and unconstrained in movement


From Middle English, flowing, from Old French fluide, from Latin fluidus, from fluere, to flow.
(American Heritage® Dictionary of the English Language, Fourth Edition)
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. (Wiktionary)



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  • Oh, man! You made me laugh so hard that ink came out of my nose.

    September 7, 2010

  • There once was a venturesome druid
    who craved a dominion more fluid
    than forest or lea,
    so he jumped in the sea
    and was eaten alive by a squid.

    September 7, 2010

  • Add to this everything that rhymes with fluid: druid, pluid, fruid, squid.

    September 7, 2010