not at all
1. Not in any way or capacity. We are not at all concerned about the impact it may have on our profits this year. A: "Do you mind if I tag along this afternoon?" B: "Not at all!"
2. Used as a polite or graceful way of accepting someone's thanks. A: "Thank you so much for helping Sarah with her studies." B: "Oh, not at all! I'm glad I could help."
not at all
and not in the leastcertainly not; absolutely not. No, it doesn't bother me—not at all. I'm not complaining. Not me. Not in the least.
ˌnot at ˈall
used to politely accept thanks or to agree to something: ‘Thanks a lot.’ ‘Not at all.’‘Will it bother you if I smoke?’ ‘Not at all.’