Толковый словарь английского языка - vertex

noun (plural vertices; also ~es) Etymology: Middle English, top of the head, from Latin vertic-, ~, vortic-, vortex whirl, whirlpool, top of the head, summit, from vertere to turn Date: 14th century the top of the head, 2. the point opposite to and farthest from the base in a figure, a point (as of an angle, polygon, polyhedron, graph, or network) that terminates a line or curve or comprises the intersection of two or more lines or curves, a point where an axis of an ellipse, parabola, or hyperbola intersects the curve itself, a principal or highest point ; summit