American Heritage Dictionary
(1)
Century Dictionary
(34)
GNU Webster's 1913
(1)
WordNet
(1)
Elsewhere on the web
Also, I am not sure whether to add Chihaya in the expanding love polygon or not.— Anime Nano!
The surface of the vast arctic plain where Phoenix landed on May 25 bears a pattern of polygon-shaped small hummocks, similar to some permafrost terrain on Earth.— dailyindia.com News Feed
Taking example of filling both color and symbols with a centriod of polygon or two languages connected to one point etc, it is proved that the effect of the concurrent markup solution for SVG.— unalog
Firstly, there's a polygon-based 2D side-scrolling shoot-'em-up.— IGN Complete
A coloured polygon is drawn to represent the size of each tremor.— Google Maps Mania

Century Dictionary (1)
Bubble size: how much this word was used in a year
Bubble height: used more or less than expected, vs. all uses evenly distributed
You can expect to see this word several times a year.