Oracle SQL keywords are not reserved. However, Oracle uses them internally in specific ways. Therefore, if you use these words as names for objects and object parts, then your SQL statements may be more difficult to read and may lead to unpredictable results.
You can obtain a list of keywords by querying the V$RESERVED_WORDS data dictionary view. All keywords in the view that are not listed as always reserved or reserved for a specific use are Oracle SQL keywords. Refer to Oracle Database Reference for more information.