1.PhraseAbsolutely not; I forbid it or it is impossible.
"You think you're getting into university with these grades? Well, forget it!; You said we could go to the mall! —Forget it! Look at the state of this room! You're going to stay here and clean up before you go anywhere."
2.PhraseIt doesn't matter.
"What were you saying? – Oh, it was nothing important, forget it."
3.PhraseA conventional reply to an expression of gratitude.
"Thank you so much! How can I repay you for your kindness? – Forget it; it was nothing."
4.PhraseI don't want to continue with this conversation (usually used in frustration or anger).
"It's raining. I said, "It's raining." Do you hear me? It's raining! Oh, forget it!"
5.PhraseDon't let it bother you; put it out of your mind.