1.
If you say that something is a big deal , you mean that it is important or significant in some way. ( INFORMAL )
I felt the pressure on me, winning was such a big deal for the whole family...
It’s no big deal.
N-SING
2.
If someone makes a big deal out of something, they make a fuss about it or treat it as if it were very important. ( INFORMAL )
The Joneses make a big deal out of being ‘different’.
PHRASE : V inflects , PHR out of/of/about n
3.
You can say ‘ big deal ’ to someone to show that you are not impressed by something that they consider important or impressive. ( INFORMAL )
‘You’ll miss The Brady Bunch.’—‘Big deal.’
CONVENTION [ feelings ]