irregular prism

irregular prism (plural irregular prisms)

1. (geometry) a prism whose cross section is an irregular polygon
   • 1867, William Chambers, Robert Chambers, Chambers's Information for the People, page 652:

     A right prism, having regular polygons for its terminating planes, is said to be regular ; an irregular prism is one in which the ends are irregular polygons.

   • 1806, Peter Jonas, The Genuine Art of Gauging Made Easy and Familiar, page 138:

     If the base be an irregular polygon of any number of sides, the prism is then called an irregular prism.

2. (geometry) a solid that is like a prism but whose cross section is not (necessarily) a polygon
   • 1850, John Radford Young, An introductory treatise on mensuration, in theory and practice, page 115:

     If the base be a triangle, it is called a triangular prism; if a square, a square prism; if a pentagon, a pentagonal prism; and' if the base is any irregular figure, it is called an irregular prism : ...

   • 2016, Kusum Wadhwa, Anju Loomba, Saraswati Mathematics, Saraswati House Pvt Ltd, →ISBN, page 234:

     Irregular prisms have a cross-section with no well known shape. Some of the steel sections used in the construction industry belong to this category.