(uncountable) The act of doing that which begins anything; commencement of an action, state, or space of time; entrance into being or upon a course; the first act, effort, or state of a succession of acts or states.
That which is begun; a rudiment or element.
That which begins or originates something; the first cause; origin; source.
The initial portion of some extended thing.
The author describes the protagonist's youth in the Beginning of the story
The house you want is down at the Beginning of the street