fluid

American Heritage® Dictionary of the English Language, Fourth Edition

1. 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.
2. adj. Of, relating to, or characteristic of a fluid.
3. adj. Readily reshaped; pliable.
4. adj. Smooth and flowing; graceful: the fluid motion of a cat.
5. adj. Changing or tending to change; variable: a fluid situation fraught with uncertainty.
6. adj. Characterized by or allowing social mobility: a fluid society.
7. adj. Convertible into cash: fluid assets.

Century Dictionary and Cyclopedia

1. Capable of flowing; liquid or gaseous; consisting of a substance incapable of resisting forces (tangential stresses) tending to change its shape.
2. Not fixed or rigid; flowing; shifting; fluent.
3. 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. A fluid has absolutely no tendency to spring back to its original shape when distorted, except in virtue of a surface tension. A perfect fluid is a fluid in which a bending stress produces an instantaneous strain—that is to say, there is no delay in taking a form of equilibrium, except what is due to the masses of the particles: opposed to a viscous fluid, in which the yielding is not instantaneous, and to a plastic solid, which yields instantaneously to a sufficient, but not to a very small, stress. Fluids are divided into liquids and gases or vapors. Gases or elastic fluids tend to expand indefinitely while preserving their homogeneity; liquids or inelastic fluids tend to expand indefinitely, but only by evaporation—that is, by separating into two parts with a bounding surface between them. (See liquid, gas, and ether.) In the early history of physical science the phenomena of heat, electricity, and magnetism were supposed to be due to the motions of peculiar imponderable fluids; hence the expressions north and south magnetic fluid, the electrical fluid, etc., which still linger (but not with good writers), though the explanation of the phenomena has changed with the advance of knowledge.
4. n. Some hypothetical supersensible substance conceived as analogous to known fluids. See fluidism.
5. n. See the adjectives.
6. n. See the adjectives.

Wiktionary

1. n. 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
2. adj. not comparable Of, or relating to fluid.
3. adj. In a state of flux; subject to change.
4. adj. Moving smoothly, or giving the impression of a liquid in motion.
5. adj. of an asset Convertible into cash.

GNU Webster's 1913

1. 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.
2. n. A fluid substance; a body whose particles move easily among themselves.

WordNet 3.0

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