1  –  CASCADE

    Specifies that you want SQL to delete the synonym definition even
    if other database objects reference this name. This might later
    cause errors when executing queries. Stored functions, stored
    procedures, and triggers that reference this name will be marked
    as invalid.

2  –  IF_EXISTS

    Prevents SQL command language from displaying error messages if
    the referenced object does not exist in the database.

3  –  PUBLIC

    This optional clause is provided for compatibility with the
    Oracle database server. It is currently not used by Oracle
    Rdb. Its presence or absence may be used by future releases.
    Oracle Corporation recommends you use the PUBLIC keyword in
    applications.

4  –  RESTRICT

    Specifies that you want SQL to abort the DROP statement if it
    detects any database object referencing this name. This is the
    default.

5  –  synonym-name

    The name of an existing synonym you want to drop.