to comfort: to ease another's grief and settle a troubled heart back into peace
This is the warm side of the word. To comfort someone is to come alongside a person in loss or pain and help them past it, so that the ache is no longer crushing. The picture is of bringing a troubled heart back to rest. It is what family and friends do for the bereaved, and it is the great promise God makes to a broken people.
The senses below differ mainly in who is doing the comforting and whether comfort is present or missing. People comfort one another after a death or disaster. God himself comforts his people, most famously when he tells the exiles their suffering is over. And again and again the text mourns the opposite: a sufferer who has no one to comfort them at all. That cry, comfort longed for but absent, is its own recurring note.
The same idea runs through the book of Job, where the friends arrive meaning to comfort him and instead become, in his words, miserable comforters, and where the story closes with his family finally consoling him for everything he had lost.