I need to create SYNONYM with name 'END'
END and REFERENCES are both reserved keywords.

So if you really want to use them as names (of tables, columns, schemata, synonyms, ...  whatever), you have to double-quote them, the same way as in Oracle:

CREATE SYNONYM "END" ... ;
DROP SYNONYM "END" ;

CREATE tab1
( name character varying(250), 
  "REFERENCES" character varying(250)
) ;


The problem is that you have to always double-quote them everywhere and match the case. "END" is not the same as "End" nor "end" nor "eNd", etc.

It would be much easier to use non-reserved words for all identifiers.