1. not at all - Adverb
2. not at all - Interjection
3. not at all - Phrase
not at all
(emphatic) Not in the least.
He's not at all friendly towards his ex-wife.
(idiomatic) Used similarly to you're welcome, as a conventional reply to an expression of gratitude.
Thank you for this very thoughtful present. — Not at all.
(idiomatic) Don't worry about it (response to worry or an apology)
Source: en.wiktionary.orgA musician would not willingly consent that his lyre should be out of tune, nor a leader of a chorus that his chorus should not sing in the strictest possible harmony; but shall each individual person be at variance with himself, and shall he exhibit a life not at all in agreement with his words? Basil of Caesarea
A nice war is a war where everybody who is heroic is a hero, and everybody more or less is a hero in a nice war. Now this war is not at all a nice war. Gertrude Stein
I am actually not at all a man of science, not an observer, not an experimenter, not a thinker. I am by temperament nothing but a conquistador - an adventurer, if you want it translated - with all the curiosity, daring, and tenacity characteristic of a man of this sort. Sigmund Freud
It is better to begin in the evening than not at all. English Proverb
A young man should not marry yet, an old man not at all. Greek Proverb
He that hears much and speaks not at all Shall be welcome both in bower and hall.”. Dutch Proverb