A1 large in size or amount（尺寸或数量）大的，巨大的
A2 informal older or more like an adult年龄较大的；长大的
C2 [ before noun ] informal used to add emphasis（用于强调）
What happened to your jacket? There's a big rip in the sleeve.
The big windows make the room feel wonderfully light and airy.
There's a big sports hall for tennis and badminton and such like.
We made a big profit on that deal.
That jacket looks a bit big for you.
A2 important, because of being powerful, or having a lot of influence or a serious effect重要的；影响大的；严重的
to be important or famous in a particular place or type of work重要；名气大
C1 informal If a product or activity is big, it is extremely popular.流行的，受欢迎的
She'll be in big trouble if she crashes Sam's car.
Her big opportunity came when she was offered a role in a Spielberg film.
His height and reach give him a big advantage over other boxers.
I must get some sleep - I've got a big day tomorrow.
Exercise can make a big difference to your state of health.