Pentagon

How to spell pentagon

8 letters · 3 syllables

How to pronounce pentagon

Say the part in capitals loudest.

What does pentagon mean?

1. nounA flat shape with five straight sides and five angles.

Pentagon in a sentence

• The geometry worksheet asked the class to measure each side of a regular pentagon.

• The home plate in baseball is shaped like a pentagon with one pointed corner.

Where does pentagon come from?

Language of origin: Greek

The word comes from the Greek pentagonon, a compound of pente, meaning 'five', and gonia, meaning 'angle' or 'corner'. Taken literally it simply describes a figure with five angles, and therefore five sides. It passed into Latin as pentagonum and reached English in the late 1500s, when writers on geometry needed precise names for the regular polygons. The same -gon ending sits inside hexagon, octagon and polygon, all of which trace back to that one Greek word for an angle, which is a useful clue when spelling the ending of any of them. In modern usage the word also names the famous five-sided headquarters of the United States Department of Defense, a building whose shape gave it its name. The pent- opening is the spelling trap to remember: it is the Greek 'five', the same root that gives us the pentathlon and the pentagram.

How the word is built

• penta- (Greek: five)
• -gon (from gonia: angle, corner)