list of all non system synonym that have no objects associated with it

[gandolf989]

Try this.

SELECT ds.owner, ds.synonym_name
  FROM dba_synonyms ds
  LEFT OUTER JOIN all_objects do
    ON ds.owner        = do.owner         AND
       ds.synonym_name = do.object_name
 WHERE do.object_name IS NULL             AND
       do.owner       IN ('SYSTEM', 'SYS');