noun

1. 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.

2. That which is begun; a rudiment or element.

3. That which begins or originates something; the source or first cause.

   “What was the beginning of the dispute?”

Synonyms: commencing, start, starting, head, start, commencement, origin, source