1. A plane figure having five angles; a fort with five bastions.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• pentegon,
• pentagone,
• pentagan,
• pentigon,
• penagon,
• pentgon,
• petagon,
• pentogon,
• pentago,
• pentegaon,
• entozon,
• pedragon,
• pendagon,
• oentagon,
• lentagon,
• -entagon,
• pentaheron,
• pentazocin,
• plantagoo,
• ennegon

• peanuts,
• pentazocine,
• pentastomid,
• pentagonal,
• pentacle,
• pentagram.

The adjective form of the word "pentagon" is "pentagonal".

The plural of the "pentagon" can be the "pentagons".

The singular of the "pentagon" can be the "pentagon".