Noun
A turning point; the principal or highest point; top; summit; crown; apex.
The top, or crown, of the head.
The zenith, or the point of the heavens directly overhead.
The point in any figure opposite to, and farthest from, the base; the terminating point of some particular line or lines in a figure or a curve; the top, or the point opposite the base.
Source: Webster's dictionaryThe centre of gravity of any cone is [the point which divides its axis so that] the portion [adjacent to the vertex is] triple [of the portion adjacent to the base]. Archimedes
If two right lines cut one another, they will form the angles at the vertex equal.... This... is what the the present theorem evinces, that when two right lines mutually cut each other, the vertical angles are equal. And it was first invented according to Eudemus by Thales... Proclus
If two right lines cut one another, they will form the angles at the vertex equal. Proclus
Proposition 3. The circle in the moon which divides the dark and the bright portions is least when the cone comprehending both the sun and the moon has its vertex at our eye. Aristarchus of Samos
Proposition 8. When the sun is totally eclipsed, the sun and the moon are then comprehended by one and the same cone which has its vertex at our eye. Aristarchus of Samos
A 0-dimensional face is called a vertex, and consists of a single point. Source: Internet