serio adverb in a serious manner IRELAND This corruption of “seriously”, making use of the familiarising suffix, especially common in Dublin colloquial speech.
[R]emembering the joy of going to school in Ireland. Wasn’t it fun? Wasn’t it grand? I miss it still. Really. Truly. Yes, I do. Serio. And monkeys regularly fly out of my butt. — Joseph O’Connor, TheIrishMaleat HomeandAbroad, p. 73, 1996