Look up “brassy” in the dictionary, and you should find a picture of Merman, the indefatigable queen of the Broadway musical for much of the 20th century. Though she made movies, some of which sent up her outsize persona, Merman was a creature of the musical theater, ideally suited to its grueling demands thanks to her big voice and bull’s eye diction. She never studied how to sing, and no less a star than Luciano Pavarotti marveled at how her voice had no register break. “What’s that?” cracked the Merm. Her debut came in the Gershwins’ “Girl Crazy,” where she stopped the show every night singing “I Got Rhythm.” Cole Porter’s “Anything Goes” (1934) provided the first of her signature roles. It wasn’t until Irving Berlin’s “Annie Get Your Gun” (1946) that she found a part fully commensurate with her talents. But it was as Rose, the ultimate stage mother, in “Gypsy” (1959) that Merman found the role of a lifetime. That such a part came late in her career only made the triumph that much sweeter.