Solutions A plain figure with eleven straight sides and angles has 6 entries with similar clues

• 7-letter words
• polygonAny plane figure with straight sides
• hexagonPlane figure with six straight sides and angles
• 8-letter words
• heptagonA plane figure with seven straight sides and seven angles
• pentagonA plane figure with five straight sides and five angles
• 9-letter words
• rectangleA plane figure with four straight sides and four right angles
• dodecagonA plane figure with twelve straight sides and twelve angles