devil
In Italian, the word 'diavolo' is used to refer to the devil or a devilish person. It can also be used in expressions such as 'fare il diavolo a quattro' which means 'to raise hell' or 'to cause trouble'. 'Diavolo' can also be used as an exclamation similar to 'damn' in English.
What the devil are you doing?
This is a phrase used to express frustration or surprise towards someone's actions. It is somewhat similar to the English phrase 'What on earth are you doing?'
He is a real devil!
This is a phrase used to describe a very mischievous or troublesome person. The idiom 'a real devil' is used in English to describe someone with similar characteristics.
Damn, I forgot my wallet!
Here, 'diavolo' is used as an interjection to express annoyance or frustration. This is similar to how the word 'damn' is used in English to express similar emotions.