1
general::
Overlook it, it's not important; you're quite mistaken. This colloquial imperative is used in a variety of ways. For example, in Thanks so much for helping? Forget it, it was nothing, it is a substitute for "don't mention it" or YOU' ? RE WELCOME; in Stop counting the changeforget it! it means "stop doing something unimportant"; in You think assembling this swingset was easy ? forget it! it means ‘‘it was not at all easy"; and in Forget it? you'll never understand this theorem it means that the possibility of your understanding it is hopeless. [c. 1900]
American Heritage Idioms
2
general::
Phrase(s): Forget (about) it!
1. Inf. Drop the subject!; Never mind!; Don’t bother me with it. • Jane: Then, there’s this matter of the unpaid bills. Bill: Forget it! You’ll have to pay them all! • Sally: What’s this I hear about you and Tom? Sue: Forget about it! I don’t want to talk to you about it. 2. Inf. Nothing. • Sue: What did you say? Mary: Forget it! • Tom: Now I’m ready to go. Sue: Excuse me? Tom: Oh, nothing. Just forget it. 3. Inf. You’re welcome.; It was nothing. • John: Thank you so much for helping me! Bill: Oh, forget it! • Bob: We’re all very grateful to you for coming into work today on your day off. Mary: Forget about it! No problem!
McGrawhill's American Idioms And Phrasal Verbs