phrasal verb. You can say that someone passed away to mean that they died, if you want to avoid using the word 'die' because you think it might upset or offend people. He unfortunately passed away last year.

Is Passed Away grammatically correct?

It is grammatical, but no, it is not acceptable. The phrase passed away is a euphemism for 'died' and is used in a formal sentence. It is not appropriate to include the cause of death with passed away, although the time and place of death may be. "My grandmother passed away from cancer last night.

How do you tell someone that their loved one passed away?

Talk slowly and gently using plain, simple language. Warning the person that you have bad news may mean that they're less shocked. It is usually clearer to say that someone has died than to use euphemisms such as 'gone to sleep' or 'gone away'.