The ALL_SYNONYMS view provides information on all synonyms that may be referenced by the current user.

ownerTEXTUser name of the synonym’s owner.
schema_nameTEXTThe name of the schema in which the synonym resides.
synonym_nameTEXTName of the synonym.
table_ownerTEXTUser name of the object’s owner.
table_schema_nameTEXTThe name of the schema in which the table resides.
table_nameTEXTThe name of the object that the synonym refers to.
db_linkTEXTThe name of any associated database link.