When I read the essay "The Opposite of Loneliness", where Marian Keegan discusses how Yale has given her that feeling, it greatly resonated with me, making me think of the times and places when I have felt the opposite of loneliness. As Keegan notes, there is no word for it, but I think we know when we feel it.
I recently read a Facebook post that posed the question: If you could spend an hour with anybody from the past, who would it be? I suspect that the question was meant to elicit the names of famous people who have influenced nations or human destiny worldwide. But my immediate response -- had I chosen to respond online -- would have been: my maternal grandmother.