It all depends whether you are using British or American English. If you translate 'pantaloni' into American English, it's 'pants'. If you translate it into British English it's 'trousers.' And as Phil says, 'trousers' isn't used in US English, and in British English 'pants' is underwear i.e. British people wear pants under their trousers.

In American English, we don't use the word trousers -- we call them "pants." In British English, I believe "pants" usually refers to a type of undergarment....