Both 可當 (前置) 限定詞和代名詞用，意為「兩個；兩者；雙方」。
在所有格 + 名詞的前面可以使用 both 或 both of；換言之，both of 跟 all of 和 half of 一樣，of 可以省略。例如：
- Both (of) her parents are doctors. (她的父母親都是醫生)
- Both (of) his sisters are living in Japan. (他的兩個姊姊都住在日本)
Both 可修飾名詞。例如：
- There are five cars on both sides of the road. (路的兩邊各有五輛汽車)
- Both children went. (兩個孩子都去了)
Both 與代名詞連用時，無論代名詞是主格還是受格，both 都位在它們的後面。例如：
- They both need some money. (他們兩人都需要一些錢) (正)
Both they need some money. (誤) - I like them both. (他們兩人我都喜歡) (正)
I like both them. (誤)