The pivotal point from which action can occur is called a catalyst. A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It provides the necessary activation energy for the reaction to proceed.
It is called the fulcrum.
the climax of the story
Its also called the turning point and the breaking point.
Melting occur at the melting point. The solid is transformed in a liquid.
The mark on the present work point is commonly referred to as a "cursor" or "insertion point" in digital contexts, such as text editing. In graphical or design software, it may also be called a "pointer" or "selection indicator." This mark signifies the current position where input or action will occur.
Such mutations are called point mutation or gene mutation.
The point on a phase diagram at which all phases occur simultaneously is called the triple point. This is the point at which all three phases - solid, liquid, and gas - coexist in equilibrium.
plot
It is called the epicenter which is the starting point.
the turning point of a event
I can give you several sentences.This is a pivotal point in your career.The battle was a pivotal one, and may decide the outcome of the war.She is the pivotal player in this situation.
The Battle of Stalingrad was a pivotal point in World War II for the German army.