Vertex n. : A turning point; the principal or highest point; top; summit; crown; apex.

Vertex n. : The top, or crown, of the head.

Vertex n. : The zenith, or the point of the heavens directly overhead.

Vertex n. : 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.

Example:
How do I find the third Vertex of a triangle when i already have two and its equilateral?

Taxonomy
corporate tax, tax solutions, Vertex, tax software, tax consulting, tax services, income tax, provision, consumer, corporate tax software, payroll tax, international tax software, Services & Consulting, corporate tax services, direct tax, indirect tax, use tax, value added tax.

Defination from the web:
Vertex income tax software.