Hoping to capture ``the special, unrealized gift of sisterness,'' fiction writer Stern (English/Univ. of Chicago; Shares, 1992, etc.) even invents a word—sistermony—to describe this extraordinary memoir of his sister's death and legacy. Four years older than the author, Ruth Stern Leviton died a long, slow death from cancer at 67 in August 1991. A sort of ``Jewish Katharine Hepburn,'' she was ``pretty, tall...cool and witty-looking.'' She was a lifelong New Yorker and had been, among other things, personnel manager and supervisor of contracts at Simon & Schuster. Stern's relationship with his big sister was comprised of ``possessiveness and protectiveness...as well as annoyance, jealousy, rivalry, and fury.'' Though much of their relationship was characterized by bonhomie and laughter, and though the more nurturing side of Ruth's sisterly love showed only rarely in adulthood, it did show up when needed, during Stern's own crises like illness and divorce. As they rehash life with their parents, the hodgepodge of aunts, uncles, and cousins, Stern realizes that he wants Ruth to tell him before she goes, about his infancy and toddlerhood, ``the life I'd lived but didn't remember.'' While it's difficult to sort out Stern's family members, his personal reminiscences of Ezra Pound and Thomas Mann, and anecdotes from decades of friendship with Saul Bellow, Philip Roth, and others are delightful and revealing. But the heart and soul of this memoir is his painstaking, progressively unsparing descriptions of the minutiae of slow dying: the injections; the draining of fluids; the black-and-blue slack skin; the munching of ice chips to relieve a dry mouth; the lapses into semi-consciousness (``Keep talking. I like to hear your voice''); and Ruth's deathbed humor (``I knew I vuzn't in duh best a helt—but diss!).'' An unheralded master, Stern has penned a small masterpiece, an intimate, cherishable American classic on death and dying—and sisterhood. (Photos)