hĭlărĭtūdo — Lewis & Short
hĭlărĭtūdo, ĭnis, f.hilaris,
I cheerfulness, merriment (ante-class. for the class. hilaritas): numquam ego te tristiorem Vidi esse: quid cedo tam abhorret hilaritudo? Plaut. Cist. 1, 1, 56:
onera te hilaritudine,id. Mil. 3, 1, 83:
ut in ocellis hilaritudo est!id. Rud. 2, 4, 8.