【正确答案】：
SUFFIXATION IS THE FORMATION OF NEW WORDS BY ADDING SUFFXES TO STEMS. SUFFIXES GENERALLY CHANGE THE WORD CLASS. FOR EXAMPLE, "EMPLOY" IS A VERB, BUT"EMPLOYER" BECOMES A NOUN WHEN THE SUFFIX -ER IS ADDED TO THE STEM"EMPLOY". 
【题目解析】：词缀是在词干上加词缀而形成新词的过程。后缀改变了词类而不是它的意思。例如，employ（雇用）是动词，但是当加了后缀-er的时候就变成了名词employer（雇主）。