Oracle ---Synonym

Creating a Synonym for an Object
To refer to a table owned by another user, you need to prefix the table name with the name of the user who created it followed by a period. Creating a synonym eliminates the need to qualify the object name with the schema and provides you with an alternative name for a table, view, sequence, procedure, or other objects. This method can be especially useful with lengthy object names, such as views.

Guidelines
The object cannot be contained in a package.
A private synonym name must be distinct from all other objects owned by the same user.

SQL> CREATE SYNONYM d_sum
  2  FOR   dept_sum_vu;
Synonym Created.

SQL> DROP SYNONYM d_sum;
Synonym dropped.