名詞 frustum:

1. a truncated cone or pyramid; the part that is left when a cone or pyramid is cut by a plane parallel to the base and the apical part is removed

frus.tum

n.（名詞）
【復(fù)數(shù)】 frus.tums 或 frus.ta [-t…] 【數(shù)學(xué)】
The part of a solid, such as a cone or pyramid, between two parallel planes cutting the solid, especially the section between the base and a plane parallel to the base.
平截頭體：切割立體的兩個(gè)平面之間的立體的一部分，如圓柱體或角錐，尤指與底邊平行的底邊或平面間的部分

來源：
Latin [piece broken off]
拉丁語 [斷的部分]