If you describe someone as manic, you mean that they do things extremely quickly or energetically, often because they are very excited or anxious about something. He was really manic He seemed to have an almost manic energy. + manically man·ic·al·ly We cleaned the house manically over the weekend
If you describe someone's smile, laughter, or sense of humour as manic, you mean that it seems excessive or strange, as if they were insane. a manic grin
affected with or marked by frenzy or mania uncontrolled by reason; "a frenzied attack"; "a frenzied mob"; "the prosecutor's frenzied denunciation of the accused"- H W Carter; "outbursts of drunken violence and manic activity and creativity"
Colloquial, to exhibit great energy, as one who is in the manic phase of manic depression