From Longman Dictionary of Contemporary Englishbig dealˌbig ˈdeal noun [singular] spoken1used to say that you do not think something is as important as someone else thinks it isIt’s just a game. If you lose, big deal.What’s the big deal? It’s only a birthday, not the end of the world.It’s no big deal. Everybody forgets things sometimes.2an important or excitingevent or situationThis audition is a big deal for Joey.3 →make a big deal of/out of/about something
Examples from the Corpus
big deal• The fact is, it is a big deal.• That may not seem like a big deal, but for me it was a triumph.• If I had twisted my ankle, would people be making such a big deal of it?• Those of an unkinddisposition might argue that mangling a non-first-class attack is not an especially big deal.• I had to adjust to not being the big deal.• He is a tremendousbig deal now!It’s no big deal• To them it's no big deal.• If you were, it's no big deal and you could have a perfectly happy life with the right partner.• If they don't work, it's no big deal.