Yes, it is acceptable to use the word "expired" as a synonym for "passed away" in certain contexts. However, it's essential to consider the context and audience when using this term, as it can have a more formal or technical connotation.
"Passed away" is a general and widely used phrase to express the death of a person, and it is appropriate in most situations, regardless of formality. It is often seen as more sensitive and empathetic, which is why it's commonly used in personal conversations and obituaries.
On the other hand, "expired" is more formal and is frequently used in legal or medical contexts, such as on death certificates or official documents. It might be used in a professional setting or when discussing formal matters related to a person's death.
In everyday conversations or when expressing condolences, it's generally better to stick with more commonly used phrases like "passed away" or "deceased" to ensure sensitivity and avoid sounding overly formal or technical. It's essential to be mindful of the tone and emotional impact of the words you choose when discussing sensitive topics like death.