BDB2173
[הוֺלֵלָה] noun feminine madness (on text see below), only plural הֹלֵלוֺת, הוֺלֵלוֺת, and only Ecclesiastes: Eccl 1:17 and I set my heart (וָאֶתְּנָה לִבִּי) to know wisdom, and to know madness and folly (הֹלֵלוֺת וְשִׂכְלוּת), compare הוֺלֵלוֺת Eccl 2:12 (|| id.); ׳ וְלָדַעַת רֶשַׁע כֶּסֶל וְהַסִּכְלוּת ה Eccl 7:25 i.e. to know folly to be madness; possibly read חוֺלֵלוּת, compare סִכְלוּת & following; the moral evil of it is specifically recognized in Eccl 9:3 (|| רָע).