1. 金字塔
    Pyramids are ancient stone buildings with four triangular sloping sides. The most famous pyramids are those built in ancient Egypt to contain the bodies of their kings and queens.

    e.g. We set off to see the Pyramids and Sphinx.
           我们出发去看金字塔和狮身人面像。

2. 角锥体；棱锥体
    A pyramid is a shape, object, or pile of things with a flat base and sloping triangular sides that meet at a point.

    e.g. On a plate in front of him was piled a pyramid of flat white biscuits.
           在他面前的盘子上有一摞摆成金字塔形状的白色薄饼。

3. 金字塔式结构（或组织、体系）
    You can describe something as a pyramid when it is organized so that there are fewer people at each level as you go towards the top.

    e.g. Traditionally, the Brahmins, or the priestly class, are set at the top of the social pyramid.
           传统上，婆罗门，或称僧侣阶级，处于社会金字塔的顶端。