vortex

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A spiral motion of fluid within a limited area, especially a whirling mass of water or air that sucks everything near it toward its center.
2. n. A place or situation regarded as drawing into its center all that surrounds it: "As happened with so many theater actors, he was swept up in the vortex of Hollywood” ( New York Times).

Century Dictionary and Cyclopedia

1. n. A whirl of fluid. An intuitive geometrical idea of the motion is not easily attained. If the motion of a flnid varies continuously both in time and in space, it may be described as such that each spherical particle is at each instant receiving three compressions or elongations at right angles to one another, and has, besides, a motion of translation and a motion of rotation about an axis through it. When this motion of rotation is present, the fluid is said to have a rotational motion; but this must not be confounded with a rotation of the whole mass. Thus, if all the parts of the fluid move in one direction but with unequal velocities in different parallel planes, though there be no rotation of the whole mass, yet the motion is rotational; and if a spherical particle were suddenly congealed, its inertia would make it rotate. On the other hand, one or more radial paddles turning about the axis of a cylindrical vessel filled with a perfect fluid, though making the latter revolve as a whole, could yet impart no rotational motion, which the fluid would evade by slipping round between the paddles. The motion being perfectly continuous, the axis of rotation of a particle must join the axis of rotation of a neighboring particle, so that a curve, called a vortexline, may be described whose tangents are the axes of rotation of the particles at their points of tangency; and such a curve must evidently return into itself or reach both extremities to the boundaries of the fluid. A vortex is a portion of fluid in rotational motion inclosed in an annular surface which is a locus of vortex-lines; and an inflnitesimal vortex is called a vortex-filament. If at any part of a vortex-fllament the angular velocity is greater than at another part a little removed along the vortexline, then (considering a particle a little removed from the central vortex-line) it is plain that of two opposite parts of this particle having the same velocity in magnitude and direction and consequently on its axis of rotation, that one which is in the more rapidly moving stratum must be nearer the central vortex-line, so that the annular boundary of the vortex must present a constriction where the angular velocity is great; and thus it can be shown that the product of the meau angular velocity in any cross-section perpendicular to the vortex-lines multiplied by the area of that section is constant at all parts of the vortex. In a perfect fluid, which can sustain no distorting stress even for an instant, the velocity of a rotating particle cannot be retarded any more than if it were a frictionless sphere; and, in like manner, no such velocity can be increased. Consequently, a vortex, unlike a wave, continues to be composed of the same identical matter. When the motion is continuous throughout the fluid, two vortices exercise a singular action upon one another, each ring in turn contracting and passing through the aperture of the other, which stretches, with other singular motions.
2. n. Any whirling or gyratory motion; also, a whirlpool.
3. n. In the Cartesian philosophy, a collection of material particles, forming a fluid or ether, endowed with a rapid rotatory motion about an axis, and filling all space, by which Descartes accounted for the motions of the universe. This theory attracted much attention at one time, but is now entirely discredited.
4. n. [capitalized] [NL.] In zoology, the typical genus of Vorticidæ, containing such species as V. viridis

Wiktionary

1. n. A whirlwind, whirlpool, or similarly moving matter in the form of spiral or column.
2. n. figuratively Anything that involves constant violent or chaotic activity around some centre.
3. n. figuratively Anything which inevitably draws surrounding things into its current.

GNU Webster's 1913

1. n. A mass of fluid, especially of a liquid, having a whirling or circular motion tending to form a cavity or vacuum in the center of the circle, and to draw in towards the center bodies subject to its action; the form assumed by a fluid in such motion; a whirlpool; an eddy.
2. n. (Cartesian System) A supposed collection of particles of very subtile matter, endowed with a rapid rotary motion around an axis which was also the axis of a sun or a planet. Descartes attempted to account for the formation of the universe, and the movements of the bodies composing it, by a theory of vortices.
3. n. (Zoöl.) Any one of numerous species of small Turbellaria belonging to Vortex and allied genera. See Illustration in Appendix.

WordNet 3.0

1. n. a powerful circular current of water (usually the result of conflicting tides)
2. n. the shape of something rotating rapidly