Reserved Words are the words that reserved by SQL for specific uses. You can't use these words as variable name or any other purposes other than the intended purpose. The following table lists the Reserved words in SQL:2003.

ABS METHOD
ALL MIN
ALLOCATE MINUTE
ALTER MOD
AND MODIFIERS
ANY MODULE
ARE MONTH
ARRAY MULTISET
AS NATIONAL
ASENSITIVE NATURAL
ASYMMETRIC NCHAR
AT NCLOB
ATOMIC NEW
AUTHORIZATION NO
AVG NONE
BEGIN NORMALIZE
BETWEEN NOT
BIGINT NULL
BINARY NULLIF
BLOB NUMERIC
BOOLEAN OCTET_LENGTH
BOTH OF
BY OLD
CALL ON
CALLED ONLY
CARDINALITY OPEN
CASCADED OR
CASE ORDER
CAST OUT
CEIL OUTER
CEILING OVER
CHAR OVERLAPS
CHAR_LENGTH OVERLAY
CHARACTER PARAMETER
CHARACTER_LENGTH PARTITION
CHECK PERCENT_RANK
CLOB PERCENTILE_CONT
CLOSE PERCENTILE_DISC
COALESCE POSITION
COLLATE POWER
COLUMN PREVISION
COMMIT PREPARE
CONDITION PRIMARY
CONNECT PROCEDURE
CONSTRAINT RANGE
CONVERT RANK
CORR READS
CORRESPONDINGC REAL
COUNT RECURSIVE
COVAR_POP REF
COVAR_SAMP REFERENCES
CREATE REFERENCING
CROSS REG_AVGX
CUBE REG_AVGY
COME_DIST REGR_COUNT
CURRENT REGR_INTERCEPT
CURRENT_COLLATION REGR_R2
CURRENT_DATE REGR_SXX
CURRENT_DEFAULT_TRANSFORM REGR_SXY
CURRENT_PATH REGR_SYY
CURRENT_ROLE RELEASE
CURRENT_TIME RESULT
CURRENT_TIMESTAMP RETURN
CURRENT_TRANSFORM_GROUP_FO_TYPE RETURNS
CURRENT_USER REVOKE
CURSOR RIGHT
CYCLE ROLLBACK
DATE ROLLUP
DAY ROW
DEALLOCATE ROW_NUMBER
DEC ROWS
DECIMAL SAVEPOINT
DECLARE SCOPE
DEFAULT SCROLL
DELETE SEARCH
DENSE_RANK SECOND
DEREF SELECT
DESCRIBE SENSITIVE
DETERMINISTIC SESSION_USER
DISCONNECT SET
DISTINCT SIMILAR
DOUBLE SMALLINT
DROP SOME
DYNAMIC SPECIFIC
EACH SPECIFICTYPE
ELEMENT SQL
ELSE SQLEXCEPTION
END SQLSTATE
END-EXEC SQLWARNING
ESCAPE SORT
EVERY START
EXCEPT STATIC
EXEC STDDEV_POP
EXECUTE STDDEC_SAMP
EXISTS SUBMULTISET
EXP SUBSTRING
EXTERNAL SUM
EXTRACT SYMMETRIC
FALSE SYSTEM
FETCH SYSTEM_USER
FILTER TABLE
FLOAT TABLESAMPLE
FLOOR THEN
FOR TIME
FOREIGN TIMESTAMP
FREE TIMEZONE_HOUR
FROM TIMEZONE_MINUTE
FULL TO
FUNCTION TRAILING
FUSION TRANSLATE
GET TRANSLATION
GLOBAL TREAT
GRANT TRIGGER
GROUP TRIM
GROUPING TRUE
HAVING UNION
HOLD UNIQUE
HOUR UNKNOWN
IDENTITY UNNEST
IN UPDATE
INDICATOR UPPER
INNER USER
INOUT USING
INSENSITIVE VALUE
INSERT VALUES
INT VAR_POP
INTEGER VAR_SAMP
INTERSECT VARCHAR
INTERSECTION VARYING
INTERVAL WHEN
INTO WHENEVER
IS WHERE
JOIN WIDTH_BUCKET
LANGUAGE WINDOWS
LARGE WITH
LATERAL WITHIN
LEADING WITHOUT
LEFT YEAR
LIKE  
LN  
LOCAL  
LOCALTIME  
LOCALTIMESTAMP  
LOWER  
MATCH  
MAX  
MEMBER  
MERGE  

Please take note that each database management system has a defined set of reserved words. Even databases from the same vendor such as Microsoft Access and Microsoft SQL Server have different set of reserved words.