create table t1 as (select user c1 from dual);
Table created.

create synonym s1 for t1;
Synonym created.

select * from t1;
T1
----------
TESTUSER

select * from s1;
S1
----------
TESTUSER

select dbms_metadata.get_ddl('SYNONYM','S1') myDDL from dual;
DDL
----------------------------------------------------
CREATE OR REPLACE SYNONYM "TESTUSER"."S1" FOR "TESTUSER"."T1"

select dbms_metadata.get_ddl('SYNONYM','S1','TESTUSER') myDDL from dual;

select 
 'select dbms_metadata.get_ddl('SYNONYM','','''||SYNONYM_NAME||''','''||owner||''') from dual;' GETMYDDL 
from dba_synonyms where table_owner='TESTUSER';