Also found in: Dictionary, Thesaurus. 1. Not at all or in any way. We are not concerned in the least about the impact it may have on our profits this year. A: "Do you mind if I tag along this afternoon?" B: "Not in the least!" 2. Not to a significantly lesser degree.

Not in the least definition: not at all or in any way. Check meanings, examples, usage tips, pronunciation, domains, related words.