NONFICTION : THE NEW HARVARD DICTIONARY OF MUSIC, edited by Don Randel (Belknapp/Harvard: $30; 942 pp.).

Since 1944, students, professionals and laymen have been dipping into the pages of “The Harvard Dictionary of Music” for the definition of some obscure musical form or the English translation of an Italian tempo marking. They did not inevitably get the right answer.

That flawed gem has now been replaced by an expanded, updated and corrected version that may well be the indispensable one-volume reference work on the subject of music--classical, ethnic, pop or rock.

Gone are the bloopers of old, like the hilarious confusion between Wagner’s “Siegfried Idyll” and his “Forest Murmurs.” Gone is the Teutonic orientation that omitted, among numerous operatic entries, any mention of a work by Donizetti or Bellini. Gone too are such cavalier explanations as this, of the nickname of Haydn’s Symphony No. 83, “La Poule” (The Hen): “The name seems to refer to the second subject of the first movement.” The “New Harvard” will tell you that the “repeated woodwind figures accompanying the second theme of the first movement suggest the cackling of a hen.”

If you must know the difference between the Lydian and Mixolydian modes, you can find that lucidly described, but not to the exclusion of a note on the practice and etymology of doo-wop.