Definition of "decagon" [dec•a•gon]

• A polygon with ten angles and ten sides. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "In Friday's edition of the journal Science, Lu and Princeton physicist Paul Steinhardt report finding a set of polygon-shaped tiles — a decagon, pentagon, diamond, bowtie and hexagon — that were arranged into distinctive patterns found on major Islamic buildings from the 12th through 15th centuries."
• "To put it simply, this bike climbs like a squirrel, descends like a greased squirrel on a luge, corners like a decagon, and accelerates like a methamphetamine-addicted rabbit."
• "These mosaics are formed from five polygons -- a decagon, a pentagon, a lozenge, a hexagon and a triangle -- each representing a unique decorative motif."