Universe is a semantic layer that maps the data structure 
found in databases(tables,columns,etc)in business terms.

A universe is a file that contains the following:
1.Connection parameters for one or more database middleware.
2.SQL structures called objects that map to actual SQL 
structures in the database such as columns, tables, and 
database functions. Objects are grouped into classes. 
Objects and classes are both visible to Web Intelligence 
users.
3.A schema of the tables and joins used in the database. 
Objects are built from the database structures that you 
include in your schema. The schema is only available to 
Designer users. It is not visible to Web Intelligence and 
Desktop Intelligence users.