not at all

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."
See also: all, not
Farlex Dictionary of Idioms.

not at all

 and not in the least
certainly not; absolutely not. No, it doesn't bother me—not at all. I'm not complaining. Not me. Not in the least.
See also: all, not
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

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.’
See also: all, not
Farlex Partner Idioms Dictionary
See also:
  • not a whit
  • not a/one whit
  • not for a second
  • not for a minute
  • not for a moment
  • not for a/one minute/moment/second/instant
  • not for a instant
  • not a bit of it
  • not a bit of it!
  • ain't