Departed is a gentle, careful way to say that someone is dead. People reach for it when the hard word dead feels too sharp for the room — in a funeral speech, an obituary, a polite mention of someone who has died. You might hear 'her dear departed husband' or 'the departed' meaning those who have died. It feels formal and a little old-fashioned; with family, many people now say passed away, or simply died. You are not making a joke, and you are not being cold; you are stepping around the blunt word on purpose. Though actually departed is also the ordinary past of depart, 'left a place' — 'the train departed at six.' That 'left' picture is where the funeral meaning grew: the person has gone. This entry is the 'has died' sense, not the train-station one.