# Definition:Pyramid/Apex

(Redirected from Definition:Apex of Pyramid)

## Definition

The vertex of a pyramid which is the common vertex of its triangular faces is called the apex of the pyramid.

In the above diagram, $Q$ is the apex.

## Also known as

The apex of a pyramid is seen in some sources (for example Euclid's The Elements) as vertex.

## Linguistic Note

The plural of apex is apices, which is pronounced ay-pi-seez.

The form apexes can often be seen, but this is technically incorrect.

Compare vertex.

Hence the colloquial phrase base over apex as the description of a particularly flamboyant physical tumble.