Sometimes we have to add new reserved words along with new features. This can cause irritation. For example, if you have a table named NONE and we make NONE a reserved word, you have to start using backticks or change the name. Beware particularly of these words that might someday become reserved according to one worklog task or another.
ARRAY ASYMMETRIC AUDIT BOOLEAN CIDR CONNECT CUBE CURRENT CURRENT_CATALOG CURRENT_PATH CURRENT_ROLE CYCLE DEFAULT DENSE_RANK EXCEPT FOR GET GLOBAL INET INTERSECT LOCAL MACADDR MERGE NEW NONE OLD OVER PARTITION RANK RESIGNAL ROWNUM ROW_NUMBER ROWS SESSION_USER SIGNAL START SOME SYMMETRIC SYSTEM_USER TRUNC UNKNOWN WINDOW
For an old list that includes reserved words in other DBMSs, check the end of an article I wrote several years ago for DBAzine, SQL Naming Conventions.
Pete Freitag’s SQL Reserved Words Checker could be interesting too.