DDD: What is the scope of the ubiquitous language? Is it domain or bounded context?
Bounded Context is where Ubiquitous Language lives.
Vaughn Vernon defines DDD in short as:
Developing Ubiquitous Language within Bounded Context
This question has been asked and answered before
UPDATE: I gave a talk at DDD Norway meetup about, covering the importance of UL and contexts. Slides can be found here.
The ubiquitous language is defined within a bounded context. This becomes obvious when you look at different BCs that contain the same term. The concept of a book in an online shop is completely different than a book in a authoring system.
From Implementing DDD by Vaughn Vernon:
Bounded Context Is Explicit and Linguistic
A Bounded Context is an explicit boundary within which a domain model exists. Inside the boundary all terms and phrases of the Ubiquitous Language have specific meaning, and the model reflects the Language with exactness.