In her new book, “The Myth of Closure: Ambiguous Loss in a Time of Pandemic and Change,” Pauline Boss considers what it means to reach “emotional closure” in a state of unnamable grief. Hard to define, these grievances have been granted a new name: ambiguous loss. The death of a loved one, missing relatives, giving a child up for adoption, a lost friend — Boss teases out how one can mourn something that cannot always be described. The pandemic has been rife with “ambiguous loss,” Boss argues. Milestones missed; friendships and romantic liaisons cooled; families prevented from bidding farewell to dying loved ones because of stringent hospital rules. A sense of “frozen grief” pervades great swathes of the global community. Boss believes that by rethinking and lending language to the nature of loss, we might get closer to understanding it.