定語用來限定、修飾名詞或代詞的.充當定語的有：形容詞、代詞、名詞、分詞、介詞短語或副詞和從句.例如：
Do you have any red ink?（形容詞）
There are many people in the park.（代詞）
He is an interesting man.（分詞）
Would you tell me your card number,please.（名詞）
He has fixed the broken bike himself.（分詞）
The teachers are talking about the teaching plan.（動名詞）
Have you got anything to say?（動詞不定式）
Can you see the car downstairs?（副詞）
He was the one who succedded in the experiment.（從句）