Definitions
from The American Heritage® Dictionary of the English Language, 5th Edition.
 noun A closed plane figure bounded by three or more line segments.
from The Century Dictionary.
 noun A train of sects whose last point is identical with the first.
 noun In ordnance, a place especially arranged for making ballistic tests of guns, projectiles, armor, and powder. Same as
provingground .  noun In geometry, a closed figure formed by the intersections of a number of straight lines, each with two others; especially, a plane figure of this sort; a figure with numerous angles
 noun two sets of n lines, each cutting all the lines of the other set upon one curve of the nth order.
from the GNU version of the Collaborative International Dictionary of English.
 noun (Geom.) A plane figure having many angles, and consequently many sides; esp., one whose perimeter consists of more than four sides; any figure having many angles.
 noun (Mech.) a polygonal figure, the sides of which, taken successively, represent, in length and direction, several forces acting simultaneously upon one point, so that the side necessary to complete the figure represents the resultant of those forces. Cf. Parallelogram of forces, under
Parallelogram .
from Wiktionary, Creative Commons Attribution/ShareAlike License.
 noun geometry A
plane figure bounded bystraight edges .  noun geometry The
boundary of such a figure.  noun geometry, more generally A figure comprising
vertices and (not necessarily straight) edges,alternatingly .  noun geometry Such a figure and its interior, taken as a whole.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
 noun a closed plane figure bounded by straight sides
Etymologies
from The American Heritage® Dictionary of the English Language, 4th Edition
from Wiktionary, Creative Commons Attribution/ShareAlike License
Examples

His mathematical friends could have told him, that though it was talked of as a polygon, it was not supposed to be a square; but _polygon_ would not have rhymed to _stare_; and poets, when they launch into the ocean of words, must have an eye to the helm; at all events a poet, who is not supposed to be a student of the exact sciences, may be forgiven for a mathematical blunder.

The term polygon is applied to figures having flat sides equidistant from a common centre.

How many diagonals can be drawn in the po? the measure of an exterior angle of a regular polygon is 30 degrees.

Measuring Po by admin on Jul. 03, 2009, under Uncategorized the measure of an exterior angle of a regular polygon is 30 degrees.

When an Englishspeaking child is confronted for the first time with the word polygon, he needs an explanation.

He took the circle to be an infinilateral regular polygon, that is, a regular polygon with an infinite number of (infinitesimally short) sides.

This is the purple polygon, which is a part of the county near Driscoll, which is affected by this.

You can see here on the radar screen, this pink polygon, that is where that tornado warning is for northwest Alabama and the cell itself really, really weakening here.

And this polygon, which is a new way that we indicate severe weather warnings out of the National Weather Service, kind of zooms it in and narrows it down just a little bit.

The next step is to see where the meteorological stations are and the assign each station an area of influence defined as a polygon whose boundary is the 1/2 way point between adjacent stations, old fashioned way of doing polygonised ore reserves so that we end up each station having an area assigned to it.
oroboros commented on the word polygon
When your parrot flies the coop?
January 14, 2011