UE(User experience design) is defined by Wikipedia

UE is defined by Wikipedia as below:

User experience design is a subset of the field of experience design which pertains to the creation of the architecture and interaction models which impact a user's perception of a device or system. The scope of the field is directed at affecting "all aspects of the user’s interaction with the product: how it is perceived, learned, and used."

Some similar user-centered design fields

Human computer interaction
Information architecture
Interaction design
Interface design
User interface design
Usability
Usability engineering
Visual design
above items incorporating aspects of psychology, anthropology, computer science, graphic design and industrial design

above info from Wikipedia

http://en.wikipedia.org/wiki/User_experience