not in the slightest; not at all
Used exclusively with a negative verb to emphasize that something is absolutely not the case, often in the phrase 夢にも思わない (wouldn't dream of it).
See also: 夢にも思わない (ゆめにもおもわない)
I never dreamed he would do such a thing.
成功するなんて夢にも思っていなかった。
I didn't think for a moment that I would succeed.
I never dreamed that he was the culprit.