MySQL CREATE FUNCTION result with multiple records gives error #1172

MySQL CREATE FUNCTION result with multiple records gives error #1172

I have the following 3 tables:
table "name"
---------------
id name
---------------
1 book
2 pen
table "color"
------------------
id color
------------------
1 red
2 yello
3 green
4 pink
table "both"
------------------------
id name color
----------------------
1 1 1
2 1 2
3 1 3
4 2 2
and I have the following function:
DELIMITER //
CREATE FUNCTION get_word(n VARCHAR(20))
RETURNS VARCHAR(10)
READS SQL DATA
DETERMINISTIC
BEGIN
DECLARE b VARCHAR(20);
SELECT `color`.`color` INTO b FROM `name`
LEFT JOIN `both`
ON `name`.`id`=`both`.`name`
LEFT JOIN `color`
ON `color`.`id`=`both`.`color`
WHERE `name`.`name`=n;
RETURN b;
END//
DELIMITER ;
now when I run SELECT get_word('pen') it returns yellow which is what is
expect.
but when I run the code SELECT get_word('book') it get error: #1172 -
Result consisted of more than one row
my Question: What to do so this function works with multiple records as
well as single record which it does when I search for "pen"? thanks