noun
frustum
Geometric term for the solid remaining after cutting off the top of a cone or pyramid with a plane parallel to the base. Often used in compounds like 円錐台 (circular frustum) and 角錐台 (pyramidal frustum).
See also: 円錐台 (えんすいだい) · 角錐台 (かくすいだい)
円錐台の体積を計算する公式を覚えていますか。
Do you remember the formula for calculating the volume of a frustum of a cone?
この角錐台の側面は台形になっている。
The lateral faces of this pyramidal frustum are trapezoids.
Compound of 錐 (sui, 'cone' or 'pyramid') and 台 (dai, 'platform' or 'base'), literally 'cone/pyramid base'. The term is a modern mathematical coinage.