spiral

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A curve on a plane that winds around a fixed center point at a continuously increasing or decreasing distance from the point.
2. n. A three-dimensional curve that turns around an axis at a constant or continuously varying distance while moving parallel to the axis; a helix.
3. n. Something having the form of such a curve: a spiral of black smoke.
4. n. Printing A spiral binding.
5. n. The course or flight path of an object rotating on its longitudinal axis.
6. n. A continuously accelerating increase or decrease: the wage-price spiral.
7. adj. Of or resembling a spiral.
8. adj. Circling around a center at a continuously increasing or decreasing distance.
9. adj. Coiling around an axis in a constantly changing series of planes; helical.
10. adj. Printing Relating to or having a spiral binding: a spiral notebook.
11. v. To take a spiral form or course.
12. v. To rise or fall with steady acceleration.
13. v. To cause to take a spiral form or course.

Century Dictionary and Cyclopedia

1. Of or pertaining to a spire or coil; like a spire; pointed or shaped like a spire.
2. Winding around a fixed point or center, and continually receding from it, like a watchspring; specifically, in conchology, making a number of turns about the columella or axis of the shell; whorled. The whorls may be in one plane, producing the flat or discoid shell, or oftener wound into a spire, resulting in the ordinary turreted form. Compare cuts under Planorbis and Limnæa, and see spire, 2.
3. Winding and at the same time rising or advancing like a screw-thread: more accurately helical or helicoidal.
4. n. In geometry, a plane curve which runs continuously round and round a fixed point, called the center, with constantly increasing radius vector, so that the latter is never normal to the curve; also, a part of such a curve in the course of which the radius from the center describes 360°. Besides the spirals mentioned below, the involute of the circle and the cyclodes are very important. The principal spirals which have received attention are the spiral of Archimedes (usually understood to have been discovered by Conon the Samian), the radius of which increases uniformly with the angle; the hyperbolic spiral, whose radius vector is inversely proportional to the angle; the lituus, the square of whose radius vector is inversely proportional to the angle; and the logarithmic spiral, whose angle is proportional to the logarithm of the radius vector.
5. n. A helix or curve which winds round a cylinder like a screw.
6. n. A spiral spring.
7. n. In wool, one of the curls or convolutions in wool-fiber, the number of which in a unit of length is made the basis of an estimate of its quality for manufacturing.
8. n. In zoology and anatomy, a spiral formation, as of a univalve, of the cochlea, etc.
9. To make spiral; cause to move spirally.
10. n. A loop in a railroad line used to overcome steep grades in a mountainous region by carrying the line through a continuously rising curve. Spirals may be cut entirely within a mountain in the form of a constantly turning and rising tunnel, the outlet being much higher than the inlet. The more common valley spirals consist of double loops or complicated curves which return and pass under or over one another, by means of tunnels or bridges, on a continuously risiug grade. The spiral loop on the Georgetown branch of the Union Pacific Railroad is an example of a valley spiral.
11. n. of a point: The origin of coördinates O corresponds to v = o, and the asymptotic points, P′ , P₁, round which the curve goes in an ever-closing spiral, correspond to v = ±∞. The intrinsic equation, expressing the relation between the arc σ (measured from O)and the inclination φ of the tangent at any point to the axis of x, is φ = ½πσ.
12. To assume a spiral form; move in a spiral course.

Wiktionary

1. n. geometry A curve that is the locus of a point that rotates about a fixed point while continuously increasing its distance from that point.
2. n. informal A helix.
3. adj. Helical, like a spiral
4. v. intransitive To move along the path of a spiral or helix.
5. v. figuratively, intransitive To increase continually.

GNU Webster's 1913

1. adj. Winding or circling round a center or pole and gradually receding from it.
2. adj. Winding round a cylinder or imaginary axis, and at the same time rising or advancing forward; winding like the thread of a screw; helical.
3. adj. (Geom.) Of or pertaining to a spiral; like a spiral.
4. n. (Geom.) A plane curve, not reëntrant, described by a point, called the generatrix, moving along a straight line according to a mathematical law, while the line is revolving about a fixed point called the pole. Cf. helix.
5. n. Anything which has a spiral form, as a spiral shell.

WordNet 3.0

1. n. a structure consisting of something wound in a continuous series of loops
2. n. a curve that lies on the surface of a cylinder or cone and cuts the element at a constant angle
3. n. a plane curve traced by a point circling about the center but at increasing distances from the center
4. n. ornament consisting of a curve on a plane that winds around a center with an increasing distance from the center
5. adj. in the shape of a coil
6. v. to wind or move in a spiral course
7. n. a continuously accelerating change in the economy
8. n. flying downward in a helical path with a large radius
9. v. move in a spiral or zigzag course
10. v. form a spiral