Begun is the past participle form of the verb "begin", meaning to start or commence something.
Common usage patterns:
1. Used with auxiliary verbs (have/has/had) to form perfect tenses
2. Can be used as an adjective in some contexts
3. Often appears in formal or written English
Example sentences:
- The project has begun and will be completed next month.
- By the time we arrived, the meeting had already begun.
- A new era of cooperation has begun between the two companies.