احتفل

اِحْتِفَالٌ also signifies The exceeding the usual, or ordinary, or the just, or proper, bounds, or degree; acting egregiously, or immoderately, or extravagantly; striving, or labouring; exerting oneself, or one's power or efforts or endeavours or ability; or the like; synonym مُبَالَغَةٌ; and so حَفيلٌ [a verbal noun of حَفَلَ]. (M, K.)

And اَحتفل, said of a horse, He showed his rider that he had attained his utmost speed of running, and yet had some remaining power. (AO, K.)