Fig.: to be very euphoric; enraptured, transported

The young athlete didn't expect to win as he was considered the underdog, so when he did win the gold medal at the Olympics he said he was on cloud nine and it would take some time for him to come down

Quando il giovane atleta, che era considerato il meno favorito per la vittoria e non si aspettava certo di vincere, ha vinto la medaglia d'oro alle Olimpiadi, ha detto che gli sembrava di toccare il cielo con un dito

When he won $100,000 with a simple scratch card, he was on cloud nine with happiness

Quando con un semplice Gratta e Vinci ha vinto € 100.000 ha toccato il cielo con un dito

The origin of this expression in unknown. It may have begun as a variation of seventh heaven, since the phrase on cloud seven, not heard anymore, has been reported by dictionaries as having the same meaning