not for a moment

not for a moment

Not for any length of time; not at any point; not at all or in any capacity. Not for a moment did I think this would be a winning ticket, so I was totally gobsmacked to find out I'd won the jackpot! A: "So, did you suspect we were throwing you a surprise party?" B: "No, not for a moment!"
See also: moment, not
Farlex Dictionary of Idioms.

not for a moment

not at all; not even for a short amount of time; never. I don't want you to leave. Not for a moment! I could not wish such a horrible punishment on anyone. Not for a moment!
See also: moment, not
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

not for a moment

Never, not in the least, as in Not for a moment did I believe he was telling the truth. This expression employs moment in the sense of "the tiniest length of time," a usage dating from the mid-1300s.
See also: moment, not
The American Heritage® Dictionary of Idioms by Christine Ammer.

not for a/one ˈminute/ˈmoment/ˈsecond/ˈinstant

(informal) not at all; definitely not: I didn’t think for a minute that he was married. Not for one instant would I ever consider going there on holiday again.
See also: instant, minute, moment, not, one, second
Farlex Partner Idioms Dictionary
See also:
  • not for a second
  • not for a minute
  • not for a/one minute/moment/second/instant
  • not for a instant
  • aint
  • ain't
  • hope not
  • (I) hope not
  • be like ships in the night
  • not by any means