The EA is:
What: The structure of an Enterprise and its blueprint describing.
How: How the Enterprise operates and the processes executed by.
Which: The technology implementing processes.
Where: Showing the location of people and technology.
Why: To streamline, align, blueprint, strategically plan, and confer agility.
When: According to the Enterprise transformation plan to a target state.
Described in artifacts such as:
Business Architecture: Products, Value Chain, stakeholders' use cases, business model, strategy, business processes, rules, orchestration, B2B choreography... artifacts
Technology & IT Architectures: Applications, Infrastructure, email, Content Management, network, SCADA... People & Organization architecture: organization chart with roles and responsibilities, culture, values... views
Information architectures and many other Enterprise views: location, planning, security…
The Enterprise transformation roadmap and its project portfolio artifacts
All mapped and linked through an EA framework.
In short though: The EA is the Enterprise structure and the operation blueprint describing the current and future states of the Enterprise, in terms of Business, Technology, People and Information views, and the transformation roadmap, process, program and portfolio, all linked together by an EA framework.
The EA ultimately will constitute the Enterprise Knowledge DB. But EA is more than the sum of its parts; it is about the governance (mind) and the culture (soul) of the Enterprise (body).