DBA_SYNONYMS

All synonyms in the database

Columns
   ___________________________
 
   OWNER
      Username of the owner of the synonym
   SYNONYM_NAME
      Name of the synonym
   TABLE_OWNER
      Owner of the object referenced by the synonym
   TABLE_NAME
      Name of the object referenced by the synonym
   DB_LINK
      Name of the database link referenced in a remote synonym

To list all the attributes for a synonym, including the object type use this query

select
 o.object_type,s.table_name,
 s.synonym_name,s.table_owner,s.owner
from
 dba_synonyms s,
 dba_objects o
where 
 o.object_name=s.table_name
 and 
 o.owner=s.table_owner
 and
 s.owner='PUBLIC'

Related:

 DBA_SYNONYMS ALL_SYNONYMS USER_SYNONYMS PUBLICSYN