Not at all!
'Per niente' — per NIEN-te. Stress on 'niente'. The 'ni' sounds like 'ny' — two syllables 'nien-te'.
Use to strongly disagree or deny something. Also used as a response to 'grazie' to mean 'don't mention it / not at all'.
'Per niente' has two functions: as disagreement ('not at all / absolutely not') and as a response to thanks ('not at all / you're welcome'). Context makes the meaning clear. As disagreement, it's stronger than 'no' alone.
Assolutamente no.
Absolutely not.
'Assolutamente no' — very firm negative — signals strong principled refusal
Neanche per sogno!
Not even in a dream!
Idiomatic — 'neanche per sogno' (not even in a dream) = absolutely not, no way
Ma figuriamoci!
Of course not! / Definitely not!
'Figuriamoci' — ironic first-person plural of 'figurarsi' — emphatic 'no way'
Italians are forthright in their negative opinions about speeches, presentations, and performances. 'Non mi ha convinto' (it didn't convince me) is a standard Italian verdict that requires no softening in informal contexts.