cones


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cone
top: right circular cone
bottom: cones and rods of a human eye

cone

 (kōn)
n.
1. Mathematics
a. The surface generated by a straight line, the generator, passing through a fixed point, the vertex, and moving along a fixed curve, the directrix.
b. A right circular cone.
2.
a. The figure formed by a cone, bound or regarded as bound by its vertex and a plane section taken anywhere above or below the vertex.
b. Something having the shape of this figure: "the cone of illuminated drops spilling beneath a street lamp" (Anne Tyler).
3. Botany
a. A unisexual reproductive structure of most gymnospermous plants, such as conifers and cycads, typically consisting of a central axis around which there are scaly, overlapping, spirally arranged sporophylls that bear either pollen-containing structures or ovules.
b. A similar, spore-producing structure of club mosses, horsetails, and spikemosses.
c. A reproductive structure resembling a cone, such as the female inflorescence of a hop plant or the woody female catkin of an alder.
4. Physiology One of the photoreceptors in the retina of the eye that is responsible for daylight and color vision. These photoreceptors are most densely concentrated in the fovea centralis, creating the area of greatest visual acuity. Also called cone cell.
5. Any of various gastropod mollusks of the family Conidae of tropical and subtropical seas that have a conical, often vividly marked shell and that inject their prey with poisonous toxins, which can be fatal to humans. Also called cone shell.
tr.v. coned, con·ing, cones
To shape (something) like a cone or a segment of one.

[French cône and Middle English cone, angle of a quadrant, both from Latin cōnus, from Greek kōnos; see kō- in Indo-European roots.]

cones

Receptor cells in the retina. They sense bright light and function in daylight. See retina.
References in classic literature ?
Beth was sorting the cones that lay thick under the hemlock near by, for she made pretty things with them.
And in August, high in air, the beautiful and bountiful horse-chestnuts, candelabra-wise, proffer the passer-by their tapering upright cones of congregated blossoms.
In addition to this, far to the south, there were other lofty cones covered with snow, which, although not known to be active, must be in their origin volcanic.
of talk and laughter--and, if you will, the Wurzburger in the tall glass cones that bend to your lips as a ripe cherry sways on its branch to the beak of a robber jay.
The servants cut our bread into cones, cylinders, parallelograms, and several other mathematical figures.
The Sphere would willingly have continued his lessons by indoctrinating me in the conformation of all regular Solids, Cylinders, Cones, Pyramids, Pentahedrons, Hexahedrons, Dodecahedrons, and Spheres: but I ventured to interrupt him.
Our instruments enable us to perceive craters, with the inner cones so common to all our own volcanoes, giving reason to believe in the activity of innumerable burning hills at some remote period.
A military organization may be quite correctly compared to a cone, of which the base with the largest diameter consists of the rank and file; the next higher and smaller section of the cone consists of the next higher grades of the army, and so on to the apex, the point of which will represent the commander in chief.
Before again issuing from it, this spiral runs into a small cone with a concave base, that is turned downward in the shape of a spherical cap.
The entrance into this metallic tower was by a narrow aperture contrived in the wall of the cone.
Does not the cone of the shadow cast by the earth extend beyond the moon?
Not the wondrous cistern in the whale's huge head; not the prodigy of his unhinged lower jaw; not the miracle of his symmetrical tail; none of these would so surprise you, as half a glimpse of that unaccountable cone, -- longer than a Kentuckian is tall, nigh a foot in diameter at the base, and jet-black as Yojo, the ebony idol of Queequeg.