Definition of "roundel" [roun•del]

• A curved form, especially a semicircular panel, window, or recess. (noun)
• A rondel. (noun)
• A rondeau. (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.

• "Another piece of information I dug out as I was reading about the roundel is that it was traditionally used by officers of arms and the military to signify nationality."
• "Above the two in the roundel is another Saint Michael bravely slaying a fire-breathing dragon."
• "Two new ones are the hex and pentagon, while the circle (once called a roundel, bezant, plate, torteau, hurt, etc., depending on its color) is simply called a circle with the correct color named."