heptagonal       
adjective uk/hepˈtæɡ.ən.əl/ us/hepˈtæɡ.ən.əl/
 七边形的
having a shape with seven straight sides
  The 50 pence piece was the world's first heptagonal coin. 这种50便士是世界上第一枚七角硬币。 
 A heptagonal pyramid is a pyramid with a heptagonal base. 七边形金字塔是具有七边形底面的金字塔。 
 See: heptagon
 - More examples
- The village has a heptagonal church.
- He might plant a new vineyard on a heptagonal scheme.
- Across the way from the church is a magnificent heptagonal keep.